This is an update on my previous post:     I had a go at rewiring the bass, and it mainly works ok. But there's a problem with the volume knob - first, it doesn't actually control the volume at all, and second there's a buzzing noise when I touch it. The buzzing suggests a grounding issue but I don't know what... Can anyone help me figure out what's causing the problem?   I more or less followed the wiring diagram below, except for a couple of changes to make the rewiri