This 70s Yamaha came in to have its wiring put back to how it was when it left the factory in 1979 (or as close as possible). There’s not much info about these but I was able to find some images of a second hand one that showed the original wiring and I was able to work it out from there. I managed to save the original pots after cleaning the wraps of wire that were around the lugs, but the switch was on the verge of falling apart so I replaced it. I also needed to use a new output jack.