onyaw

Hi - simple question i hope. The master control volume on my spider valve 112 is very crackly when i turn it (maybe some other knobs too). i was going to very lightly spray in some cleaner around the stem but I can't get the knob off and i read in another post not to pull too hard because they're right on the circuit board. how to get them off/how to clean the pots from the outside? that other post referred to a video on the site but i can't find it. thx. onyaw