Krups EA826 leaking water through the drawer

This machine is about 6 years old and for the last year it sat on my workbench waiting to be fixed. I finally got to it about a month ago. The first problem was the mill, which I replaced. I also replaced the two O-rings on the piston, which appeared to be worn. I also replaced a tiny O-ring that is located on the outlet from the piston. It wasn't necessary but I had it anyway. I checked the bottom seal - it is in excellent condition.

So, when I run a rinse cycle, perhaps 20 or 30 ml of water gets into the cup, and some into the drip tray. However, when I try to brew a cup of coffee, very only 5-10ml of coffee gets into the cup. The rest of it makes a terrible mess by running over the top of the brewing unit, through the drawer and the puck container.

The line between the piston and the dispensing nozzles is not obstructed in any way.

I disassembled the piston thinking that perhaps it is clogged washed it carefully and put back together. There is a tiny black rubber valve in it. I tried to blow through it, which did not work, but carefully poking with a toothpick seems to have opened it ok.

I am stumped. Please help !!!

Hello
, you also need to change the seals of the hydraulics and the seal of the tappet piston (sits at the bottom of the brewing chamber). On Ebay there are seal sets for under 10€.
Instructions for disassembly are available on Youtube.