It happens: You’re cleaning up your guitar or bass or you’re doing some kind of maintenance on it, and you need to remove the control knobs. But one of them won’t come off. Here’s what to do and what not to do.
First, if you haven’t done so already, do check to see if the knob is held on with a setscrew. If it is, use the right size (small) Allen wrench or flathead screwdriver and make sure the setscrew is sufficiently loosened.
If the knob still won’t come off whether there’s a setscrew in it or not, do not try to pry it off using a screwdriver or a knife or whatever other suitable implement seems up to the task, because you could damage the pickguard, the top of the body, the knob itself or the potentiometer the knob is attached to. Don’t attempt to free it using pliers or an adjustable wrench, either, because that’s another good way to damage the instrument.
Since most people aren’t experienced luthiers with specialized tools designed specifically for loosening stubbornly stuck control knobs, here’s what you should do: Wrap a cloth around the knob and carefully try to work it free that way. The cloth will give you more leverage, and that’ll often do the trick.
If that doesn’t work, don’t risk damage by more forceful attempts at loosening a stuck control knob. Take your instrument to a qualified professional for repair.