Siemens TK76K573: coffee cycle interrupted

Hello
,We have a Siemens espresso machine model TK76K573
.

When we want to make a coffee/expresso, we have the following malfunction:
- The cycle starts-
The coffee is ground-
The water is pumped, heated and then sent to the "valve" (part 0543 / 00654842
)- The hot water is sent to the ground and compressed coffee ("passing group", part 0711 / 00741901)


...




but very quickly (1 to 2 seconds) the water is redirected (by the "valve") to the "tank" (part 0113 / 00704177) via the "Recipient" (part 0529 / 00647106) and the cycle stops

We initially thought that the "valve" or the "passage group" had a defect

.

These two parts were successively changed without result.

In addition, to help with the diagnosis
:- When the "hot water" or "milk frother" program is selected, it works correctly-
The fault arrived gradually

.

At first it was one coffee out of 10, then one out of 2-3 and finally it stopped working.

We suspect a defect in the control board (aging / faulty / out of order electronic component) but given the price of the board and the parts already changed unnecessarily, help/advice from someone who may have encountered the same malfunction would be welcome

.