so I moved a few months ago and had a small hum in the right channel that I could get to go away if I fidgeted the tube around, and after a while of annoyance I retouched a bunch of the connections and replaced a few wires. I fixed that hum, but now, there's a hum in the left channel as described in the manual, but this hum only appears when the volume is turned down - it vanishes at max volume, and progressively gets louder as the volume is turned down... do I have a bad pot? I haven't tried touching the connections there yet, as the wire is pretty brittle and I don't have enough to replace it all currently, but how would I tell if this is a potentiometer problem or a problem somewhere else in the signal chain? I have the Speedball installed, by the way
