Power supply to transformer

Hello everyone, I have a Jura F8 that does nothing more for a few days, so no power supply, I know relatively well with such machines have several revived, now it is so with this F8 that a varistor with the designation 14 D 431 K is burned out and has left a black imprint on the board, the varistor sits in front of this small black rectangular box he most likely protects,I soldered another varistor with the designation S 14 K 275 that I had left over in the expectation that it would work, unfortunately there is still no current at the transformer, so at the input of the transformer coming from the board there is only 9 V, there should be 230 V coming in and going out 15 V and 9 V, so the transformer is OK and the fault is still on the board, can it really still be the varistor because it is not the right one? Next to the varistor is still a small fuse or what that is, was also completely verrusst but has passage, so that is also okay, can someone give me a hint what is still in question?