There are many solvents for use in those ultrasonic cleaners. Just verify it is compatible with the rest of what you want to clean. Evaporust can be used straight in there for de-rusting iron and steel parts. The cleaner will markedly speed up the process and also the micro cavitation will get the part clean and keep them clean. Dilute citric acid for the copper and coper alloys. Get this from Amazon, "Brass Mate". This will immediately clean brass and coper and it is a dip in and 10-15 seconds later pull it out and rinse. If you want a shine then light polishing with any of the cotton wadding polishes will finish it off or rub down with a coarse cloth and paste wax.

Plastic, once cleaned with something such as electric automatic dishwasher soap and a shot of dishwasher performance booster they can be brought to a high polish with a string buff and jewelers rouge. If you do have to polish them after initial cleaning be sure to clean them again to get all the polishing compound off of them.

Machining the spring decompression tool

I finally managed to get access to a lathe. The little drill press I bought simply did not cut out for me, so I instead brought it to my college's mechanical engineering workshop. With the assistance of a Lab TA I learned how to use a lathe for the first time.


My tool started as a grade 5 100mm M18 x 2.0 steel bolt. I originally bought three of these and I already goofed up the first one at home with the small drill press. The second attempt involved me fiddling with CAM software and try tapping and cutting on a Hass lathe, but there was an error with the tool holding the tap and at the last moment messed up the thread. I did learn a fair amount from that attempt in machining so I still considered it a success in that regards.

My last bolt was properly cut. Just to note there are multiple thread types for the gaggia pinion thread on top. The ones currently in the groups are M12 x 1.75 thread while the old new stock I purchased are M12 x 1.5. Since I had one left I used the M12 x 1.75 tap as I currently do not intend to switch out the pinion racks unless there is an unseen problem coming soon. After boring out the inside of the M18 bolt 2" deep with a 27/64 drill bit, I took the hand tapping tool and attached a spring loaded shaft behind the tool and loaded it into the lathe for stability and to ensure my tap was straight. It was quite fun to do actually and I hope I learn how to do more stuff like this as I go through this restoration.

You will be really a certified addict when you have your own lathe in your shop. A lathe with attachments is probably the most versatile tool you can have.

Oh boy I don't want to look into the price of one of those right now!

I finally have my tools to take apart my groups, which I will post a highly detailed post once at least one group is completely in pieces. I am currently having an issue with removing the spring from the piston. I was able to take off the piston and spring easily enough with my fashioned spring compressor tool, but in this particular group there is the infamous brown powder stuck inside. I am not sure what exactly happened but it appears to be very old coffee grounds or residue that somehow gummed up the piston and spring. The spring itself is very rusted and weak, and is absolutely stuck to the piston. I have taken the heat gun a few times to heat it up and nothing happens besides more powder coming out smoking a little. Are there any ideas on how to wrestle out the spring so I can have a replacement placed when I am assmebling the groups post-cleaning?


All of this powder was from inside the group and represents maybe a 1/4 of the total that came out so far.

Nevermind, I figured it out. I asked Russell Kerr what he does and he said to rap the spring with a hammer on all sides to knock loose the grime/rust while laying the piston on its side. It came out after about a minute of doing this and nothing was damaged! To be sure I did not use too much force I used a half-sized hammer. Looking at the piston shaft I noticed it appears different than what I expected. Instead of the traditional rack design it is something slightly different! I will need to check that out more.

edit: in the end the rack was a standard design, the bottom spring retainer was just very stuck.

Mechanical agitation and heat are the first choices for unsticking things. Several days in EvapoRust will get rid of the rest of it.

Disassembling the Gaggia Group
Probably one of the most notorious parts of wrestling apart a lever machine is the group disassembly. I will document here how to do it and overcome this stigma so if you ever need to do it you have a general idea of how to do it!

The tools you will need are shown in the following photo, but listed they are:
10mm socket with socket extender
Hammer or mallet
Two wrenches to hold the spring tool
Heat gun
5mm allen key
3mm spigot tool
Flathead screwdriver
Bearing Extractor
Spring Compression Tool


Some suggested tools but not necessarily needed for this procedure:

7mm wrench for the shutoff valve
An extra pair of hands if the group is already off the machine

The first thing you will need to do is lock the lever into the preinfusion setting, so that the top nuts are not holding the rack system. Take off these two top nuts and insert the spring compression tool with an appropriate washer and padding (I used a ¾" washer with paper towels).


Unlock the lever and allow the spring tool to rest on the top of the group. Take off the lever itself using a wrench. This may require some force if you have already not loosened or taken off the lever in the past. I used a flathead screwdriver with rubber padding and leveraged it off between the group and the lever cam. Take off the locking mechanism as well.

There are two spigot screws you will need to take off. It is likely gunked with coffee oils and be stuck. Simply take a heat gun and use it for 30-60 seconds and it will cause the oils to become liquid and even may act as a lubricant when unscrewing. I had to file down my spigot as it was originally 4mm, a far more common size than the 3mm diameter for the ones on the group.


Taking off the spigot caps will reveal two bearings inside, most likely covered in grease. You will take the 10mm socket attached to the socket extender and with a hammer whack the pinion rack on the left side of the group when facing the front. Sometimes a normal hammer will not be enough, even after applying the heating gun multiple times. This is where you get a bigger hammer (within reason. You do not want to shatter the mechanism with TOO much force). I used a hammer whose head is lead. Group 0 me 1. The cam as you can see is quite jammed up with grease and was why I had so much resistance.




Take the same 10mm socket w/extender and rap the left bearing from the inside with a mallet. The right bearing will come off with the pinion rack and require a bearing exractor to remove.



The reason you need to take out the pinion gear is the rack teeth do not go all the way up to the top of the rack. If it did you could simply unscrew the top and the piston would be able to be taken out afterwards. A downside to this is that you would have no control in how rapidly the pisting would come and could go flying due to the spring force. Hence the teeth end. Unscrewing the piston while keeping the rack in place would simply stop decompressing the spring once you reached the final tooth, and may put strain on the pinion gear teeth.

Now you can start decompressing the piston the entire length. You may need another wrench or a pair of pliers to keep the M18 bolt from moving with the nut you are unscrewing as well. In this process you may need to put the group on its side as the piston will eventually start supporting the group from its height as the spring relaxes. When you are able to unscrew the nut by hand you can take off the spring tool and pull the piston out of the group


The remaining steps involve taking off the 80mm nut that compresses the gasket stack inside. You need to unscrew three worm threads with a 5mm allen key to loosen them from the threads. If they are stuck apply some heat and wait a bit. I was fortunate in that the hex nut unscrewed easily enough but I needed some leverage to separate the top of the group from the hex nut. I used padding and copper teeth in the vice to prevent my metal stock or the vice from damaging the parts.


The gasket stack is the lasting thing you remove. You may have the worm thread block the shimmies and brass sections of the stack, so you would need to tap it from the inside to make it flush with the sleeve. Presuming anything is asbestos either mist the stack or wear a proper mask with a fan blowing away from you. I think the fibrous gaskets are cotton but I like to take precautions. Bag up the stack afterwards.



And you have a disassembled group. You may still need to take off the shut off valve but for me they are both absolutely fused to the group on my machine, so I will need to address that in a different manner.

Good info. The cleanup will be almost as much fun as the disassembly.

My even bigger problem is/was/will be getting of the groups from the boiler - on all my machines the steel bolts were so corroded in the brass body of the group and the seals between group and boiler were like concrete glue... major PITA
Any tips for that problem?

I did not have rust issues to your extent when taking off my groups from the boiler. However they were initially still stuck to the gasket. What I did (and only discovered accidently) was I loosened all of the hex caps screwed on to each bolt. Over the course of a month I would pull the levers down to cock them while playing around with it or testing some ideas. In that process the strain of pulling down like that eventually loosened the group flange from the boiler so that when I took off the bolt caps the group was already loose and could be removed. If yours is stuck as you say it is there will be some more work required beyond what I did. I have been very fortunate so far in not encountering any serious issues in disassembly (just look at Paul's Orione restoration thread for an idea...). Going to that thread may also help you out as well.

Gaggia Orione restoration