If you recall this thread Elektra Microcasa a Leva, coffee + grams + tamp? about the problems I had with my used pre-1997 McAL, I could not get it to stop jerking on the way up when you pull a shot. Cleaning, re-lubing, degreasing, changing gaskets, changing groupheads, changing portafilters, nothing worked for more than a week or two.

Well, after my Faema Carisma broke down again (it kept blowing fuses, they finally relented and sent me a new control board, which fixed the problem) I decided to revisit the McAL. I lubed and cleaned everything and it worked for a week. After that I slowly took the spring-piston out without moving the lever, and I thought I had found the problem (recall, this is a pre-1997 unit but it has a post-1997 spring). I thought the new spring, with its larger inside diameter, was shifting in the group and hitting the side wall, thus causing the jerking. When I pulled it out, the spring was all the way to one side.

I purchased a new (post-1997) piston, piston pin and top plate. I installed them. Worked like a dream, better than before. The coffee was amazing, the pull felt great. A week later, it was back to the jerking. So, I am asking again, in a last bout of desperation, does anyone have any ideas on what could cause this? I have again ordered two more gaskets for the piston (I had new ones on the old one, which I installed onto the new piston) and the gaskets should be here next week, but I am now really out of ideas. I have changed it all (grouphead, group, piston, piston pin, top plate, portafilter, gakets).

What I am doing: using 14.5grams of good fresh espresso and grinding it in a Mazzer super jolly. I am not really tamping as much as I am using the OE method of knocking it on the counter and then using the tamper to flatten out the top. When I pull a shot, I pull the lever down and start to count... after about 9-10 seconds a drop will come out. I release the lever and if I want a "large" I almost immediately pull it down again, if not I let it go up. It takes about 20 seconds to rise fully, so we are talking about a 30 second shot. It all looks great and tastes great, until the lever starts jerking.

I will note further, when it is jerking, sometimes the piston will need help to get all the way down again (you can push on the pin form the top)... so it seems to me like something is really stopping it. The portafilter screen looks clean and well.

Ideas?

I recall the original thread but don't remember if you ever mentioned how long you persisted using it with the jerky lever. I think I mentioned that I had experience something similar after installing new seals on my Sama Export, and found that it resolved after a week or so, of pulling 1-2 shots per day. I installed a brand new PV spring when I rebuilt the Export and noticed that when I replaced the seals maybe a year later, the spring was noticeably distorted to one side.

It seems to me that the problem is that the seals are grabbing the cylinder walls for some reason. Are the seals good? What about the walls of the cylinder? What about the cylinder wall lubrication?

Elektra has stern warnings with a new machine about using inappropriately contaminated water. The space above the Piston in these machines is dry, not surrounded by live steam or filled with water as it is in many other machines. Pollutants in the water get into the pores in the brass. The water dries out and deposits salts on the walls. Here is what I would do:

I would remove the piston assembly and dispersion screen. I would take some "Bar Keeper's friend", Brasso, or similar material and carefully polish the full length of the bore. I would wipe the bore with a cloth wet with 190 proof alcohol after that. (Sold in Rum shops as Everclear.) I would clean the piston assembly thoroughly. I would put a thin film of the standard silicone lubricant (111) on the piston seals. I would put a really heavy coat on the UPPER part of the piston that contacts the cylinder wall. I would put the piston back into the cylinder, pushing any lubricant that stuck on the top of the cylinder assembly back into the bore against the piston. I would finish the assembly.

Unless I were already using water with no impurities but potassium bicarbonate I would dump the contents of the reservoir and refill it with 1.0 mMolar potassium bicarbonate in pure distilled or properly deionised water. I would not consider putting water with detectable chloride in one of these machines! If I were a fan of dark roast I would simply use straight distilled or deionised water, dark roast coffee lacks acidity. About the least corrosive aqueous solution against brass or copper is very dilute bicarbonate with an anion that has a soluble carbonate. It buffers the pH to a bit above neutral, and ZnCO₃ may form on the surface from the Zn in brass to help stabilise. Unlike tap water you can adjust KHCO₃ to taste. (Coffee has very low sodium and very high potassium. (To my taste at least, there is a slight taste shift when even fairly small amounts of Na is present in brew water, so I use potassium rather than sodium bicarbonate. Wine makers use KHCO₃ for pH control for this reason.) As I have described before, I make a 10% solution of potassium bicarbonate in a small stock bottle. Add 1 mL of this per litre of brew water using a small pipette.

As you aready changed group, piston and rod, my bet is on a sort of misalignment of the piston rod on the cylinder.
Yes, but due to what?
maybe a deformed fork of the lever?
alberto

I would find that pretty tough to believe. I also have two forks and have tried them both, but they are both loose and don't cause the piston to do anything strange. When you clean and lube it, there is no fork sticking or pulling (I really checked this out a while back). I am also aware of the problem of the roller pin sliding and not turning, and I am making sure that mine turns and not slides on the top plate.

I now keep thinking: grease, gasket problem, grind/tamp problem (why would it not do it right off if it were a grind/tamp problem?), voodoo put on it by previous owner, I'm doing something terribly wrong, Elektra gods hate me. My neighbor is Italian and he is from Italy. I wonder if I can have him talk to it; maybe it's homesick?

More seriously, I am going to try rpalvis advice for now and see how that works out this weekend.

Mine (1980's with (only) new spring) does it with some coffees sometimes - mostly when I do multiple pumps ('Fellini'). The piston bore is worn near the bottom - not obvious by feel, but by the change in colour from brass to copper.

I usually pull singles so it doesn't bother me - but I guess I could hone the cylinder if it did.

YMMV.

I don't remember if in your long previous thread you posted a video.
It could be useful to well understand what's happening.

Here is the original video. It is doing basically the same thing now, but it just started doing it. I have not yet pulled the piston out again and I am waiting on a new set of gaskets right now.

https://www.youtube.com/watch?v=JfbVS42 ... e=youtu.be

It's a really strange behaviour.
I don't think that gaskets can do this alone.
Unless they are wrongly assembled on the piston or badly inserted in the cylinder.
It seems that there could be a metal-metal friction instead.

UPDATE and some questions.

I received the new piston gaskets. I installed them. After about a week, the McAL began to jerk again. Last night after letting it cool I changed out the grouphead with my last remaining grouphead (I have three, can you believe that?) This morning when I made an espresso, the lever came up so fast it was shocking. I reevaluated the situation (I am measuring the beans by grams and am using the same system of tamping all the time), and turned the grinder to a more fine setting. Second come slowed down a bit, but still too fast. Lunch time comes, dialed the grinder down some more. Ok, I am back at about 30 seconds for a double.

So, we shall have to wait and see if this new group starts to jerk. I have a question however. As seen in this video, albeit on a different machine completely, I note that this person seems to be tamping really hard. If I go searching for lever videos, they all seem to tamp REALLY hard. Like these people are moving their weight over the portafiter. I have taken to using the OE method of using a funnel, getting the grinds in the portafilter, knocking it on the counter a few times and then using the "no pressure" method where you just flatten the top of the grinds with the tamper. This seems to work fine, and the espresso is great.

Am I doing this incorrectly? Is this causing some problem? Should I go back and start over and grind a lot more coarsely and tamp harder? I adopted this OE method after seeing some video on it while researching the Pharos, IIRC.

Thank you.