Buzzing sound while turning volume switch.

Thanks guys for the advise. I'll open up the unit to do some spraying as what Detlof recommended. Anyway the unit was almost 3 years old.

Bob and Zaikesman give good advice to my mind. Sometimes merely working the control end to end several times can help and make the buzz go away. If that does not help, unplug the unit from the mains, wait a little if it is a tubed unit, open it up and do the spraying yourself. (If the unit is new, which I doubt from what you say, you may however void its warranty)

*IF* the buzzing isn't present when you're not touching the unit, *AND* it's fairly low in level when you are, I wouldn't worry about it too much, as it's probably just one of those little grounding anomolies having as much to do with the AC line and the combined other gear in the system as the component itself.

have a knowledgable tech spray the volume pot for you with an oil-free cleaning solvent (& then work the control end-to-end several times before the spray dries - tech should know to do this). If the symptoms continue then move on.

You should contact Angela at BCircle@BlueCircle.com
Tell her I send you if you want.

Or there's a loose connection. The BC21 is wired point-to-point and some of the components are supported by the wiring. I had a similar problem with a BC 21 which deteriorated into more noise. Cured with one dab of soldering iron. Open it up and look for something loose, probably connected to volume control.

either the amp too old or your place too humid (like seashore or near hill)

need to get tech man to clean the blemishes (if any)