I've just done some major repairs on my Pavoni and after replace the group washer, C-clip and 2 piston gaskets with ones from the standard Service Kit, it seems like I've lost suction pressure pulling water into the group. The smaller diameter sides of the piston gaskets are pointing together and the group washer is facing upwards.
I can pull a below-average shot by relying on the high-temperature water pressure from the tank to push into the group, but I can remember it used to pull the water into the group on lever raise.
Now when I raise the lever, unless it's hot, the group doesn't seem like it's filling, but dripping in. The air-holes into the group are clear and everything seems normal, however the pressures not there.
Any ideas where I can look or what I can check next?