yeah  some people say that the boards are shorting  against the coffin case.  i stil sat clean the switch and pots while you have it apart though.  i would jost so i didnt have to take it apart twice. oh and one more thing   beforeyou take all the boards out of the coffin case. mark all the plugs  for direction  with a magic marker.   there  directional but can be put in backwards.  i know  i did it.  got a  clicking noise and couldnt  figure it out till i took it all apart again.  mines all marked up for that now. it will be apart for a while so i dont  want to do that again. im transplanting into a lucite body. by the way i didnt mean to say the switch  was necessarily dirty.  but might be oxidised. like a  scratchy  tone or volume control gets  when it gets old.   ive even taken those apart  and  emeryed the  contact  and  the bottom of them .  clears that scratchyness right up like a new pot.   well good luck  let me know how it comes out.