I have a 1980s model Peavey T40 with the blade style pickups. Recently, I noticed that when the pickups are in single coil mode (tone knobs above 7) they have become very noisy. I am think it might be single coil hum, but, when the pups are set at the same tone and volume levels they still sound noisy. When the bass is in humbucker mode (tone knobs at or below 6) the noise disappears. The noise decreases if I roll off one tone knob only. Sometimes, if I move the bass to a different position, the noise is exacerbated. I have plugged the bass into various amps and used several different cables. On a recent trip to the guitar shop I had the pots cleaned. I asked the tech what he thought and he seemed to think it was normal. I am not sure about that, I think this noise is a recent development. Suggestions? Thoughts? I love this bass too much to it sit idle.