If you know the thread trimmer does not work you can do a couple of things to find the component that is not working. 1. Use thermal imaging to see if one of those transistors is super hot or super cold (also can be used to see if another IC chip is bad) 2. Use a meter to compare with another working unit. I can say from just repairing an Adler 195 with a variocontrol that the common transistors with that one are (from left to right) 1,2,3,5,6,7, and 8.