There is zero chance this filter has anything to do with the issue and zero chance better filter will help. You need to fix the controller, I'd start from checking if button switches did not become somewhat conductive in open state. Or program selector encoder might be bad. How did you determine that original filter is out of spec? Did X capacitor lose capacitance or what?
>> X capacitor lose capacitance or what"
Yes, that's correct "
>> There is zero chance this filter has anything to do with the issue and zero chance better filter will help.
I had a similar conversation with a forum member (not here) about the same topic approximately 4-5 years ago.
I remember another instance in the past when I had a similar issue with a dishwasher. The symptoms were errors in the middle of the program, or even worse, the selected program would run for hours without completion. I had a hard time finding the root of the problem on the PCB. All the parts seemed fine, except for the XY polypropylene film capacitors. Once I replaced them, the machine worked perfectly and is still running smoothly today.
I suspect EMI/RFI interferences can cause problems in microcontrollers that are very hard to spot in some circumstances, especially when the PCB design is poor.
>> I'd start from checking if button switches did not become somewhat conductive in open state. Or program selector encoder might be bad
Yes, I was thinking of that too. I will try 1st this capacitor and then I will check/replace the program selector encoder. I didn't check this part and I am not sure how to do it. It is cheap ~10 euro so I might replace it in the end.