Buzz on toggle switch

[oldmanp03]

I have an 81 G&L L1000. The previous owner switched it out with active pickups in it(not sure brand). It has a 3 way switch. Saturday night we were getting a nice buzz going through our IEM's.....it would go away when I would move the switch to the middle position and hold it in place.

Any idea what would cause this? ANd what I could try to remedy it? Could it be a grounding issue inside?


Thanks.