Does anybody here know what might be causing the volume levels on a 1954 Valco Tube Guitar Amplifier to not respond normally to adjusting the volume levels. The level position (eg. 9pm is the loudest and 3pm is most distorted and weaker signal, and anything inbetween is also weakest.)
When you move the volume knob is it accompanied by a crackling sound ?
Volume potentiometer probably needs replacing. You could try using a switch cleaner spray but on something so old it's likely to be more than a dirt problem. Not very expensive for a service guy -- or you could just unsolder the whole volume control unit yourself and replace with one of the same value (that should be printed on it).