Is the "knob" bad or the selector switch? Replacing the switch would be a lot of work, so try a good cleaner/lubricant that has been suggested.
Replacing selector knob
The selector knob on my integrated amp is suddenly making a lot of noise and not really letting the signal through. Can this be fixed or can the knob be replaced with a better piece?The company is out of business, so going through them is not an option.