[Ron Ramirez]

If you can get to the backs of the controls, unless they are sealed shut there should be a tiny opening on either side of the terminals where you can spray some contact cleaner into each control, then turn it several times through its rotation. Repeat for the volume control, bass and treble controls (or tone control if it does not have separate bass and treble).

DeoxIT D5 is best for this job.

Do not spray anything on the set's tuning condenser! Also, do not spray anything near hot tubes. This should be done with the set off and unplugged, when it is cooled off. And do not power the set back up for awhile after you have sprayed the controls; give the cleaner a chance to evaporate, which takes a while if you're using DeoxIT.