I also had problem with ceuise control until yesterday. It wasn’t problem to turn it on, but I couldn’t set speed and if it was succesed, it could disengage by himself after 100m or 2-3km. Tryed to adjust rear brake swich, disassembled and cleaned front brake swich (there is nothing to clean:)). Found some topics in internet that problem can be in sticking front brake swich and allmost ordered new one, but wanted to check everything once again. And I foun a problem: mu cluch cable was too loose and cluch handle didn’t come back to its normal position, so cruise control sensor was in disengaged position almost all the time.
PS all swiches has two clicks - first for cruise disengaging, second for brake light or to say to ECU that cluch disengaged.
PPS sorry for my english, but in my opinion this is helpfull info