With the disappointing demise of the Epressi company, we are now on our own to maintain and repair our Mypressi TWISTs, the handheld espresso makers. This post is intended as a guide to repairing a unit that leaks gas as soon as a gas cartridge is inserted. For me, this symptom was independent of, and not affected by, manipulating the trigger mechanism in any way. If you have a Mypressi that loses gas when the trigger is pulled, then I cannot guarantee that this repair procedure will solve it - but it might.

Symptom addressed by this post:

• Gas continuously discharges somewhere inside the handle as soon as a new cartridge is inserted.

Symptoms not specifically addressed by this post:

• Unit infuses normally when trigger is pulled partway but then there is uncontrolled leakage of gas when trigger is pulled all the way.
• Continuous uncontrolled gas discharge does not occur until trigger is pulled. It may or may not stop when trigger is released.
• Pulling trigger does not release gas for infusion.
• Pulling trigger results in stuttering or interrupted gas flow.

Please note:

• The procedure for replacing the pressure engine o-rings that solved my unit's gas leakage problem may solve or improve the four other problems - or it may not. There are other parts of the pressure engine that did not seem relevant to my problem and I did not investigate them, but they may be involved in the allied but separate symptoms above. If someone were to open and recondition these other areas, they may find the solution to their problem. Remember, there is really no 'trigger' problem as such. The trigger is just a lever. All of the performance parameters failures occur in the pressure engine. The only problem with the trigger is if it binds in the engaged position and does not return to rest due to something that is bent, out of alignment or corroded.

Fixing the gas discharge problem:

• There are three ways in which a Mypressi commonly loses gas: one trivial compatibility issue and two malfunctions. The malfunction most frequently mentioned is a 'blown gasket' in the pressure engine. There is also the possibility that the o-ring that seals the neck of the gas cartridge has deteriorated.

Fix #1 - Cartridge compatibility issue:

• Gas cartridges are not perfectly standardized; there is a reported 0.5 mm difference in lengths. If you occasionally have a cartridge leak or lose gas pressure during short term storage, the fault may be that you have a minutely shorter cartridge that is not snugged all the way into the nozzle dock. It does not hurt for all TWIST owners to invest in a roll of thick foam double-sided sticky tape. Cut off a square of it and adhere it to the butt of the gas cartridge; leave the cover on the other sticky side (image below). Insert the cartridge as usual. The thickness of the foam core is all that is needed to snug the cartridge nozzle into the dock a little bit more. If that solves any gas leakage problems, then place the next square of tape inside the hollow end of the screw-on cap of the TWIST handle, sticky side against the inside of the cap and, again, leave the covering plastic on the side that contacts the butt of the cartridge and you will not have to put a square on every cartridge that you use.
  
  Now on to malfunctions. When my TWIST began to leak gas, the handle felt cold and it gave the impression that gas was issuing from the tip of the punctured cartridge; that is how I presented the problem to the Mypressi help desk. Even if you are sure that this is your problem, it may not be and it is worth your while to determine exactly from where the leak emerges.
  
  For both malfunction problems, carefully pry off the 'left' plastic shell of the handle (the one with 'mypressi' and the logo on it) with a thin screwdriver or a dull knife. This is the procedure that most owners hate because the plastic shells are epoxied on and they cannot be replaced without gluing them back. No one has complained of breaking the plastic shells by prying them off, but just be careful and pry a little bit at one edge location and move to a different part of the edge and pry a little bit, move and pry, move and pry. The shell should come off without breaking. You have now exposed the pressure engine and the metal plate securements. If you happen to visualize a 'blown' o-ring extruding from under the pressure engine lid (below), you may dispense with the following water-dunking step and go right to disassembly.
  
  Not all blown pressure engine seals will be visually apparent. To visualize the gas leak location, begin by filling a sink or bucket full of water. Insert a new gas cartridge, screw the cap on and dunk the entire handle completely underwater. It helps if the water reservoir, spout and basket are not on the handle. Locate the leak. If the leak is issuing from the back of the handle or the securement over the neck of the cartridge, you may get away with replacing only the o-ring in the dock at the neck of the cartridge. If the leak is issuing from the pressure engine, you should recondition and replace the pressure engine components. If the gas leak is coming too fast and is disturbing the water too much to get a good visualization, just wait until the leak slows down and you should be able to locate it accurately. The more involved repair procedure of the pressure engine will be described first as 'fix #2'. If you are now pretty sure only the docking o-ring needs replacement, skip to 'fix #3'.

Fix #2 - Pressure engine malfunction:

• I did this repair in the kitchen of a high-rise apartment and I am all thumbs. You do not need general shop or machinist skills nor do you need expensive tools or power tools.
  
  Here is what you will need:
  One o-ring, 13.0 mm x 1.5 mm, Buna-N or equivalent, stiffness of 70 (medium)
  One o-rings, 8.0 mm x 1.5 mm, Buna-N or equivalent, stiffness of 70 (medium)
  Three o-rings, 3.5 mm x 1.5 mm, Buna-N or equivalent, stiffness of 70 (medium)
  Two o-rings, 4.5 mm x 1.5 mm, Buna-N or equivalent, stiffness of 70 (medium)
  One o-ring, 8.5 mm x 2.5 mm, Buna-N or equivalent, stiffness of 70 (medium) for the cartridge dock, if you want to replace this (i.e., fix #3).
  Two small screws, stainless steel, 2.5 x 6mm flathead countersunk Philips
  Good quality small Philips screwdriver with sharp bit, best if it has a square or hex portion to the shank or lever attachment to the handle for extra torquing force (to unscrew)
  Small plastic bags (I used snack size Ziploks)
  Silicone o-ring lube
  One sheet very fine sandpaper (800-1000 grit)
  Cotton or gauze
  Digital camera or phone camera
  Blunt probe (see instructions)
  Fine tweezers or forceps
  Citric acid or vinegar
  3m Scotch-brite or equivalent scouring pad (blue, green, maroon or white, doesn't matter)
  One fine-tip hemostat if you want to replace the docking o-ring (fix #3)
  Small brad nail
  Small or regular hammer
  
  Some people would like to see an exploded schematic of the inside of the TWIST handle. It helps for general orientation. Other than that, it is of little help in disassembling the engine. Here it is:
  
  http://cdn.shopify.com/s/files/1/0169/4 ... _Guide.pdf
  
  The picture below is my exploded diagram, showing the lid off. You can see the three 3.5mm o-rings on the horizontal trigger cylinder (two posterior, one anterior) and the two 4.5mm o-rings on the internal cylinder. The orientation of the small side hole on the internal cylinder doesn't seem to matter on reassembly (following picture). Mind the small spring inside the internal cylinder; don't lose track of it.
  
  
  To get here, remove all of the bolts holding the pressure engine and the trigger assembly onto the handle and keep the bolts in a safe place. Everything will come right out. It helps to take pictures as you disassemble the handle components; that way, reassembly is not guesswork. To remove the trigger assembly from the pressure engine there is a little trick. It is held in place by a cheap pin that is made from rolled steel. I tapped it out using a small hammer on a drift pin (pushing pin) which was a small nail (called a wire brad) held with the head against the rolled pin and tapped it until the pin moved enough to release the trigger assembly. Whatever you do, do not put the point of the nail into the hollow center of the rolled pin or you will spread it and it will be hard or impossible to slide it back in. Use a wire brad or blunt equivalent whose dimensions match the diameter of the rolled pin. Pound on the point end, if using a nail. Below is a picture of the pressure engine with the rolled pin still in the mounting flange.
  
  The brass nozzle is attached to the trigger assembly by a similar rolled steel pin. Partially move that one out of position by the same procedure and free the brass nozzle from the trigger. Leave the rolled pin hanging in the hole of one flange of the trigger unit.
  
  When you have the brass nozzle free of the engine, remove the old o-rings and soak the nozzle in acid and scrub it to remove the mineral scale. My favorite o-ring removal tool is a blunt cake tester. A pointed object may score the brass or cut into the o-ring.
  
  Here is a detail of the flattened, blunt tip of the Cake Tester:
  
  Use vinegar or citric acid and scour with a nylon pad only. Do not use steel wool. The metal dust would be uncontrollable, often too fine to see, and may possibly ruin the pressure engine.
  
  Use a good jewelers screwdriver or other small quality Philips screwdriver to remove the Phillips screws from the pressure engine top lid. If you use a screwdriver with a good fit, you may get them out without buggering them - I buggered one and so bought two replacements. If you get the bolts locally or order them on line, you will have to specify the metric dimensions (above), but also specify Phillips head and countersunk. This size only comes fine thread, but you may have to specify fine thread if there is a choice questionnaire. They are hard to get started to remove because they have been glued in with a thermoplastic sealer - Loctite Red. You will hear a !snap! as they release to come out. This is why a sharp Phillips bit and a screwdriver with a lever advantage makes the job much easier. It also helps to push down firmly while you are turning, so as not to slip and deform the screw head. A vise to hold the engine while you wrestle with the little screws is a godsend, if you have one. I didn't, so I built a cradle out of rags to hold it steady and upright against my pushing down while turning and I put it on the floor. I kept the engine from turning by wedging it between two boards. If you have access to a good vise, stabilizing the engine while you remove the screws is much easier but be careful to cushion the engine by using softwood boards between the vise jaws; if you overtighten the metal jaws on the cast metal engine body and crack it, the game is over. Philips slots are designed to 'cam out' (slip out) if too much torque is applied and that is why you stand an excellent chance of damaging them during any removal and why replacements are likely worth the trouble of ordering. Theoringstore.com only carries o-rings, so you will have to order the screws from some other online source. You have all of the parameters that you will need to order them. Try to find a web site with reasonable shipping/minimum order requirements since you only need two, about 14 cents worth. These are too small to be stocked by local hardware stores, including the big box stores, but you may luck out and a local hobby shop or unique mom-n'-pop store may have them. Trouble is, not only are they small, they're metric. EU Mypressi owners have an advantage in this regard.
  
  Take a picture and make a note of the fins (flanges) on the lid and know which way to return them because the lid can be fastened in both orientations. When you get the lid off, the mating surfaces look a little cruddy. More on that later.
  
  About the o-rings. If you live in Maryland, then your best bet is Maryland Metrics in Baltimore. Maryland Metrics will have both the o-rings and the screws and, yes, they mail order, but I was local at the time so I don't know how easy they are to order from by mail. There is no other metric distributor like this in the US. Otherwise, theoringstore.com has every o-ring that you need, plus silicone lube. This is the place that will ask you what stiffness you need. The stock o-rings are 70 (medium) and this is what you need. Do not order 90 (firm) thinking that they will last longer. There is anecdotal evidence that stiffness 90 may not seal as well. Theoringstore.com also has a variety of compositions. For our purpose, Buna-N and Teflon (or PTFE) are equivalent food-grade compounds. I think the Parker o-ring lubricant stipulated by Mypressi.com is hard to find and is way too expensive. The stuff that theoringstore.com sells looks just as good and I would use that if I were you, since you will be ordering from them, anyway. To lube all of the o-rings without any mess, I put them into a small Ziplok bag with a small amount of the lube and mash them around that way instead of getting it all over my fingers (photo below). Remove the o rings from the Ziplok with tweezers.
  
  Next, you want to clean the mating surfaces of the engine body and the lid, so try to find 1000 grit sandpaper, at least 800. Maybe a hobby store might have a smaller pack than Lowes or HomeDepot. But first, you will want to stuff cotton or, better yet, surgical gauze into the bolt holes and, more importantly, the pressure engine holes in order to keep the sanding grit out of the mechanism. Do not skip this step. Below is a photo showing the tarnished mating surface of the engine with the protective cotton wads in place:
  
  First though, moisten the cotton or gauze with the o ring lube in order to keep all of the fibers sticking together - you don't want to introduce those fibers into the pressure engine, either. The white in the ziplock picture below is the mess-free Ziplok lubing procedure applied to the cotton I used.
  
  Make sure none of the cotton is sticking out where it can get caught in the sandpaper.
  
  As far as polishing the mating surfaces of the engine and lid, place a sheet of the sandpaper on a perfectly smooth surface such as a pane of glass or a Corian kitchen counter (not tile or wood) and rub the mating surface of both the lid and the engine on the paper until reasonably shiny.
  The following photo shows the lid surface half way through sanding. Notice that the ends have shined up but not the middle. There is a miniscule amount of metal warp here which will be eliminated by the sanding, improving the seal. It wasn't demanding or tedious.
  
  Remove the cotton with tweezers or tease it out with a pin when finished and pick away any stray fibers you may see.
  
  Use a magnifying glass. Do not skip the magnified visual inspection; you may be surprised. Below is the finished engine surface showing stray fibers:
  
  Lid surface when finished:
  
  The photos below show the receiving cup (called the 'pressure release tube' on the pdf schematic) attached to the handle chassis by two screws with a black line between it and the silver cup-like port in front of it. This is the 8.0 x 1.5 o-ring and you should unscrew the rear cup from its position, replace the o-ring and replace the cup.
  
  
  When the internal brass piston and external brass nozzle have been descaled, the three 3.5mm ID lubed o-rings have been replaced on the brass nozzle, the two 4.5mm ID lubed o-rings have been replaced on the internal cylinder, the mating lid and engine have been polished, the protective cotton or gauze has been removed and the engine holes have been cleared of any stray fibers, then it is time to reassemble the engine. Refer to the photo showing the exploded diagram of the parts (above) ready for reassembly. Note that the fins on the top of the engine lid are closest to the observer; this is the correct orientation of this otherwise symmetric part.
  
  One important detail to be considered is that there is a deposit of Loktite red thermoplastic still at the bottom of both screw holes. This will prevent the screws from tightening down all of the way and, unless they do, the gas leak will not be fixed. It is procedurally impossible to dissolve or scrape out this deposit from the depths of the tiny screw hole. The easiest solution is to heat up the ends of the small screws, or the entire screw, and allow it to melt the thermoplastic as the screw penetrates to the bottom of its screw hole. This will also serve to reseal the screws into place, just as before. You are strongly cautioned against trying to remove the Loktite red manually or chemically, since this is highly likely to damage the screw hole threads in the former case and make reusing the residual thermoplastic impossible in the latter. There is no way to get it all out. Also, do not buy or use Loktite blue (the most commonly available product) since this will also interfere with heating up the screws and the ability of Loktite red to re-secure them.
  
  If you do not have a torch, full butane lighter or gas stove at your disposal, turn one element of your electric stove on high after placing the two new replacement screws onto the element, being sure to place them in such a way that they will not roll off and that will allow them to be picked up with tweezers or forceps without burning yourself.
  
  Leave them on high for a full ten minutes; you will not damage the screws and should not damage an electric burner that is in normal operating condition.
  
  Place the spring that fits inside the internal piston and insert the piston into its well; the orientation of the piston side hole is not important. Lubricate the 13mm o-ring well but not sloppily and press it into its oval recess. Spread a thin film of silicone lube on both mating surfaces of the lid and engine. Replace the lid onto the top of the engine, checking to make sure the large o-ring stays in place. You can prevent the internal spring from raising the lid back up by putting a small rubber band around the engine. In a pinch, a strip of Scotch tape wrapped twice around the engine will do. Have the Philips screwdriver standing by.
  
  If you have a flame, grab the Philips head of the screw at the end of the jaws of the hemostat and click the hemostat handle once into the locked position. Make sure the hot screw won't jump off. Heat up the thread end of the screw with the flame until the finish of the stainless steel turns dark, or for a total of ten seconds. You do not need to make the screws red hot, in fact, I wish you wouldn't. Holding the screw by the hemostat, insert it into the hole and turn the screw using the hemostat until it is well into the hole. Quickly remove the hemostat and screw the bolt all the way down as tight as you can comfortably make it. Unlike removing the screw, you don't have to use the same force needed to break the seal. Moving quickly but deliberately, heat the second screw and screw home in the same way.
  
  Now reattach the brass nozzle to the trigger assembly using the rolled steel pin. It should look like the photo below, ready to reattach to the engine (except note that the engine lid is on backward; the highest part of the top fins ought to face rear. Oops.).
  
  Reattach the trigger assembly to the engine body by carefully reinserting the lower rolled pin. Replace the large nozzle spring. It should look like the photo below, and this time the lid is in proper orientation.
  
  All the work is done and it is time to fasten the engine into place. While the curved metal plate that constitutes one half of the handle end cap screw socket is still off, now would be a good time to replace the cartridge dock o-ring seal.

Fix #3 - Cartridge Seal Replacement:

• Whether you are refurbishing the engine or just replacing the cartridge seal, you need to take off the left-hand plastic shell from the handle and remove the curved metal plate that covers the cartridge seal and dock in order to get access to the circlip (spring clip) that secures the o-ring. If you do not have an internal spring clip pliers, you can get one fairly cheap at Harbor Freight or online, or, for less money, you can use a hemostat, but get one with thin jaws. A mini hemostat or mini gator will not be strong enough for the circlip and its jaws was bend - get a regular size hemostat. Only once was I able to engage the internal spring clip down the well of the cartridge tunnel without it slipping out of the hemostat jaws without having to access the clip by disassembling the handle as described above. You can try the easy approach, but it won't be quick and after the circlip rings slip off of the hemostat jaws enough times it would be best to access the clip with the dock cover removed. Contrary to what the Mypressi TWIST cartridge seal replacement guide pdf above says, you do not need to remove the engine to get to this o-ring and remove it. The following picture shows the handle with the curved metal plate dock cover with its two securing Philips screws removed:
  
  The photo below shows the C-shaped dark circlip, half hidden by its position in the recess, with scratches evident on the end rings from past removal. Below this is the thick silver retaining washer over the o-ring, which can be seen as a black line below the silver washer. Below the o-ring is the silver base of the handle well with the penetrating spike sticking up in the middle:
  
  With the hemostat or ring pliers jaws through the circlip rings, squeeze the handles of either tool together until the ends of the circlip touch each other and the curve of the circlip should be reduced enough for you to lift it out and away from the recess groove that holds it in place. This is a good time for you to move your work to a carrel or to the corner of the room, because if that dark circlip decides to spring out of your grasp, it will do so faster than the speed of light and it may take you a long time to find it again, and I do not know the dimensions for a replacement, so please don't ask me. Put it aside and use the hemostat or forceps to lift the silver flat washer that lies under the circlip away from the o-ring seal that lies beneath the washer. Replace the o-ring with a freshly lubed 8.5 x 2.5 o-ring. Place the silver flat washer back on top of the o-ring. Pick up the circlip with the pliers or hemostat and move it into the cylinder dock. Only then squeeze the ends together once again and maneuver the curve of the clip into the groove above the flat washer. You may have to squeeze the clip with one hand and use a probe (like a skewer or a cake-tester) to push the washer down away from the groove and/or guide the curve of the circlip to the level of the groove before slowly releasing it. Usually, only the back curve of the clip lies within the groove while the ends remain above the groove but it is stable in this position and you can use the tip of the hemostat or something else to push the circlip ends down to the groove where they will click into place. Done. Bolt the curved metal dock cover back onto the handle and replace the plastic handle shell.
  
  Securing the handle shell:
  
  Espressi directs us to apply epoxy to the handle holes that mate the black plastic pins of the handle in order to keep the shell on. Do this if you wish. It might make it more likely that the pins could break off the next time the handle was opened. It is likely to need periodic maintenance just as any other espresso machine would. If you have made it this far, then you have earned your stripes as a Mypressi Veteran. If you wish to join the ranks of the insouciant toocooltocare, then just double twist a thick rubber band around the handle to hold the shell in place and have done with it or, for that high-tech look, include four or five 40mm ID o-rings in your order and roll them over several spots on the handle. Or, you might consider sheathing the whole handle with 50mm heat shrink tubing from a site like hobbyking.com.
  
  The key points are: the small screws are stuck in with thermoplastic Loktite, so it is absolutely essential to have a good quality, perfectly fitting small Phillips screwdriver bit with sharp edges, to have the pressure engine 'cradled' for stability on a firm surface so you can push down hard and turn until you hear the !snap! of the sealant giving way. A good screwdriver handle or wrench attached to the screwdriver shaft (which would then have a hexagonal or square shank portion for this) also gives a leverage advantage.
  The next key point is to occlude all of the openings with lubed cotton, paper or cloth in order to keep the sanding debris out of the machine and to check the holes for stray fibers after the wads are removed.
  Also, do not put the screws in cold, put them in hot, otherwise the lid won't seal.

That would be it.
Good luck, either way.

BT

We have a few sets of Mypressi V2 gasket sets sitting around if anyone needs them. Send me a PM.

That is good to know!

Take out the 260 watt soldering gun and apply the tip to the screw head and heat it up until hot, will now come right out. Works for those coarse thread screws directly into plastic that either twist off or the plastic explodes.

I second that, for those who have such a gun handy. 140w gun might even work.
B

Probably would if they are not too large. Most Loctite gives up at something over 225F or so.

I do have a Mypressi Twist, but didn't read every word, tl;dr, because I don't currently have the problem, but it looks like a great write-up and a resource for Mypressi Twist owners. Thanks for taking the time to document this, I may need this later.

Hi Buckley, first I want to thank for his willingness to help all those who have a Mypressi with a leakage problem. I did the procedure guided by you to dive to dip the Mypressi in a bowl of water and realize hence the leak. Identified leakage from a part fastened by two screws situated on the outside below the location where the gas is inserted. To facilitate the understanding I have attached some photos. If you can help me, thank your commitment.

Grateful.

Dear Cristiano,
It is my strong wish that this post - or separate posts like it - will begin to spring up on H-B to cover the whole world of Mypressi maintenance. I cannot do it alone - it will take collaborators such as yourself to complete this 'Epressi-wiki'.

What you are illustrating is terra incognita to me.
However, I am interested in your situation which, admittedly, is of no help to you.

I have two suggestions which might be of help.

1. You might try to track the owner, Stephen O'Brien, down on the web and see if you can locate him and see if you could correspond with him or one of his engineers. It would be nice if they were pleased by the continuing popularity of their out-of-production product and responded to the continued public interest by an 'heirloom fix-it guide'.

2. Given that the possibility of success using #1 is unknown but not expected to be high, I would forge ahead. After all, the only real help the Mypressi help desk was to me was to give me the dimensions of the o-rings and bolts. With a little more trouble, I could have matched them on my own through trial-and-error or finding a sympathetic supplier. Since you have begun dis-assembly, I would photograph everything as you are doing for your own peace of mind for reassembly, but also to post a thread as I did in the (likely!) event that you are successful. All you need to do is to mind seals and corrosion; replace the former and eliminate the latter. It is possible that you might have to invest in small hand tools or bits.

I would experience vicarious fascination from seeing pix of the parts of the pressure engine that you have exposed, especially if you were of a mind to accept the challenge and to "boldly go where no home barista has gone...". I think we all would enjoy that.

With Kindness,

Buckley T