I discovered something today which may also be relevant to vintage basses having a squealing issue from the rotating the filter knob. i say relevant because i found it epeatable and solveable ,so it can be one more thing to check if you experience. I opened the back of my control cavity, which has the PF card and control knobs in a single cavity and when i put the cover back on and played, the squeal appeared but this time the frequency changed with knob position. However on the second half of travel there was a lovely warm frequency dependent raspy synth like sound that wouldn't be out of place on something by Jean-Michel Jarre, early Chick Corea or Kraftwerk. 👍🏾😂. When i opened up the cavity again i noticed the pickup connecters must have been in contact with the back of the pots or some other exposed wire. After putting Insulation tape over the connectors, all back to normal. I tried it a couple of times off and on and the issue is repeatable. i recorded sample which i will drop on to soundcloud so you can enjoy the vibe. 🥳. Hopefully no damage will have occurred.
