When I turn up the volume on my MIM Fender P, it get a buzzing sound. This sound goes away when I touch the bridge, knobs, or strings. In an effort to get rid of it, I have replaced the volume and tone pots, as well as the factory wiring. The difference in sound and clarity is noticeable, but the buzzing is still there. I've called the local shop and the guy said it's normal and present in all electric instruments. Somehow I don't believe him. It sounds like a grounding problem. Anyone have any advice? All wiring has been triple-checked.