KRUPS EA80

Hello
, I have 2 KRUPS EA80 coffee machines which have the same problem:
At the end of the production of a coffee, water remains (or arrives) in the chamber. When the piston goes back down, there is a projection of water inside then this water starts to boil creating a lot of steam inside.

I have cleaned everything and disassembled the bleeding piston (drain valve), but I don't know what to do to repair it. I tried another one that I had without more success.
The
pump sends water by blows but no steam
.
I tried to pass a small wire through the holes, it does not come out. Same thing for water or air. I am listening to

all your advice because I do not see on the net any answer to this problem

.



Thanks in advance

The problem is not visible when the coffee maker is in normal operation with ground coffee in the percolator. In this case there is no water left and it does not boil.
But I don't know if this is normal!