Volume controls get old and make noise exactly as you describe. USually they an be cleaned with a shot of fader lube (usually found with guitar stuff, ir common electronic cleaning stuff.
Other types may be nore 'elegant. but fader lube is the stuff you need, or like it.
Where the volume control is, inside it.., spray fader lube.
After ten years my Bryston BP-26 volume is making noise when moved. But is perfect when not turned.
PS. turn it off.. and turn the volume back a forth a LOT many times. the turn on. Is the noise gone??? Then fer' sure you should get fader lube. as the noise will be back in a few days..