You can remove the piston from the shaft by simply turning it by hand. That plate showing water level will probably turn with it. The spring then decompresses fully. SO if you want to simply change the piston seal, don't do the above or you'll have to figure out how to compress the spring and reinstall the brass piston. I don't think putting it back on will be as easy as taking it off. Any advice here would be welcome.

But that leaves the piston with the seal still sandwiched and you'll have to get or make a tool to fit the pin holes (pin spanner or pin wrench) and a way to grip the other end without damaging it (a lathe chuck or collet chuck).

Jack, your encouraging words led me to go through the trouble. You were lucky-- your voltage worked and your machine wasn't a wreck. Mine was pretty much a wreck... So I had to decide whether to cut my losses (smart) or fix it (don't know yet how smart).

dan

Its actually a good candidate for a complete renovation like you've proposed. The plastic case for beginning, is quite flimsy and cracks easily. I do like the logo though, and the timeless 70's elegence. of the shape. But it took a long time to like it.

My time it completely limited, so I don't do any restoration work on any machines right now. I have a dream about re-making my PonteVecchio case in stainless or some nice paint, etc. SOmeday....

PC

It doesn't seem to be easy to turn by hand on my machine, so I already was thinking on how could I compress the spring without the piston...

My goal is to add a smaller spring to improve pressure. I know I can help the lever but that's not so practical to day use. I've used the machine some days after I cleaned it. BTW, the boiler without some seal doesn't work. I have some silicon rubber here, but it's 2mm thick - too much for it. I'll probably use Loctite 518 as a flange sealer, as advised by a clever HB member to me.

Márcio.

There is a gasket tape
[url]
http://www.mcmaster.com/#standard-gasket-tape/=b6j83j[/url]

that looks like a good solution. Better than the Loctite.

I still don't see a nice way to compress the spring and hold it there. I'm thinking of just putting the spring in a vise and compressing it. Then tying it closed with wire. What I don't know is what happens when I cut the wire... I'm a bit afraid that the spring will open quickly and lopsided.

I'm sure Doug at OE has and idea or two? I could also make a special compressing tool, but if I can avoid it, that would be better. There isn't a way to easily get a couple clamps around it and the top of the boiler. If I haven't figured a better way by early next week, I'll try the wire idea.

I think that, maybe, the thread size of the rod is enough to compress the spring back, similar to Zerowatt. I think the displacement is very small. I will try to remove it, and if I can't put it back then I think about something...

Oops, indeed I'll have trouble to install the spring back! You have to compress around 16 to 20mm to reach the rod thread, probably 30 kgf...

Well, spring removed and measured. It's 120mm long, 47.7mm external diameter, 5.05mm wire diameter, 6 coils. Seems to be stainless steel. Should I consider 6 or 5.5 coils? On the spring designer calculator I'm using, if I put 5.5 coils it gives almost the exact weight of the spring, and a little bit more force to compress it.

The spring installed has 78mm (42mm displacement) and with the lever fully pulled it has 44mm (76mm displacement). So the pressure of the Mini Gaggia seems to be from 5.5-6 bar to 3-3.4 bar (considering 6 or 5.5 coils). No high accuracy here, but it makes sense for those who use the machine, right?

Maybe a 5.5mm wire, keeping the external diameter, could fit (36mm is the minimal diameter to the spring fit the top of the boiler) and it should give from 8.8 to 4.8 bar. But I think a additional spring could improve the maximum pressure without adding pressure to the pin when the lever is up. There is a spring shop that has a 25mm diameter, 3.5mm wire, with 78.3mm size and 9 coils, that could give around 3 bar when compressed 34mm. I could test this one.

Considering one should put 60 kgf more, and the lever to pin ratio seems to be almost 1:9, that would require 7 kg more over the original 12 kg (seems to be ligher when I pull it).

Márcio.

I remember now that the piston only seal the chambe and push the water after 10mm down... So maybe the maximum pressure on the puck is 4.5 to 5 bar...

Márcio.

Can anyone tell me how to get the feet off this thing. I managed to pretty much break the plastic feet out of their metal surrounds which exposes a large slotted screw head but I can't budge any of them. Is that how people are supposed to get them off? Perhaps they're just too rusted to the frame.
Sam.

Too much rust. Mine turned freely, and were excellent, in fact, in setting the machine to the proper angle for stability while pulling the lever.

Maybe some anit-rust lubricant and time?

Thanks Peacecup. So yours just turned by hand I guess. My frame and screws are quite badly rusted so it looks like I'm in for some work. I suspect I may have to break them off by whatever means and find some other feet later on. I've tried penetrating oil but they're pretty bad.