Another way to keep the group screen clean is to cut a natural sponge so it fits in the portafilter with basket. Soak it in JoGlo or other coffee detergent, then pull some water through it. This creates a soft backflush. The idea was suggested by Richard Penney, who makes wonderful bottomless portafilters.

Thanks for this. It's time for some maintenance on my Pavoni and I've been wondering how best to do this.

ill try it...

what about removing the dispersion screen. how do I remove it?

I would like to get to the piston and keep it lubed

It is really amazingly easy to service groups on these machines. It is especially easy if one replace the two pins on the group handle with anything else! One approach is to thread a 6mm brass rod and put acorn (dome) nuts on either side. One can also get an appropriately sized fairly decorative bolt of the appropriate length, or cut a longer one. This also allows tightening the bolt so that it it has less "slop."

It is extremely simple to remove the group from them too. Some have been found to have shorter group securing bolts than La Pavoni's own specifications. One can get longer bolts in this case or replace them with stainless or brass threaded rods. This is important because one needs to service these machines fairly frequently, and the threads can strip. (Mine started to do so.)

Remember again to use something like DOW 111 for the plastic to metal or plastic to plastic, but use high pressure lubricant for metal to metal points.

Third generation machines with polyphenylene sulphide piston wall sleeves do not have cylinder wall pitting problems, but these plastic sleeves have a finite life time. I suspect that this is partly due to the high pressures applied to the group walls during pulls.

+1

rpavlis wrote:It is really amazingly easy to service groups on these machines. It is especially easy if one replace the two pins on the group handle with anything else! One approach is to thread a 6mm brass rod and put acorn (dome) nuts on either side. One can also get an appropriately sized fairly decorative bolt of the appropriate length, or cut a longer one. This also allows tightening the bolt so that it it has less "slop."

For the above you could thread a brass rod, secure it with acorn nuts and add washers to remove the lever slop. The outer washers would be stainless steel, the inner Teflon to avoid abrading the lever fork.

Vc wrote:what about removing the dispersion screen. how do I remove it?

That's what I tried to explain in my post #10 above. Maybe didn't get it across very well there. See Greasing the group? for a more careful description of how to do that.