bsafnuk wrote:Has anyone come up with the cause of these bubbles? I am getting the exact same problem with my Pavoni. Somehow the group is not expelling all the air at the top of the stroke - I know this because the lever is quite soft for the first part of the pull.

Anyways, I am baffled as to what is going on - I have brand new seals on the piston, the handle is installed right side up. The bubbles appear regardless of freshness of roast (both with coffee roasted 2 days ago and with Illy preground coffee). The only variable I haven't ruled out is replacing the gasket where the piston shaft leaves the group. However, I cannot envision how a problem with this gasket would lead to air in the cylinder. There are no obvious signs of problems here (no water leaking out the top, etc.)

Anyways, if someone has some suggestions, I would be very grateful.

-Brad

I was getting the same problem with my Pavoni as well, very little resistance the first part of the stroke and bubbles at the end of the second stroke. In my case the solution was replacing the upper seal in the group head (under the brass retainer ring). This was the only gasket in the group head that I hadn't replaced earlier and it was really worn out. I agree it seems a bit far-fetched that this could lead to air in the cylinder but for some reason this seems to be the case. Also, another nice side effect is that lifting the handle is now much smoother.