Jura XS95 - coffee amount too small

Thanks in advance for the advice!

I have a used Jura XS95 that only makes about 1/3 of a portion of coffee before the rest of the hot water leaks into the drip tray.

When the cycle starts, coffee flows into the cup as normal. After about a third of a cup, the coffee flow trickles off and hot water begins to leak out of the bottom of the brew group into the drip tray.

I have disassembled, cleaned, lubed, and replaced all the seals in the brew group. I have replaced the drainage valve and the lower piston.

I have changed the grind density from fine to course and back again with no change in problem. I have used pre-ground coffee in the bypass as well with no change to the problem.

I have run out of ideas,.... Thanks for the help!