I have a Sansui AU-717 Integrate Amplifier. When I turn the volume knob, one or both of two things happens. Either one of the channels shuts down or I get a crackly output. I have been told that there is something that you can spray on the knob device on the inside of the case. Is this true and, if it is, what is it called and where can i find it?

Skyfyre