Interesting guitar wiring problem

[Randall]

My Gibson Les Paul decided to start to buzz when the pickups were turned down and it wasn't being touched. I looked into it, and found an interesting failure. After scratching my head for a while, I found that the 4 conductor shielded cable that runs from the control cavity about 16" up to the pickup selector had lost it's connection between the foil shield and the bare ground wire. So instead of shunting EMI to ground, it was acting as an antenna. I found if I pinched the wire with pliers in a couple of places it would quiet down, so I'm guessing the foil shield must have oxidized and failed. I have never seen this before.