Hi Bob,

The usual approach to cleaning a volume control is with a straw from a spray can.
And, it is, in my experience, a repeat maintenance with old equipment like this.



The control has an opening to each section through which you can flood using the thin straw to direct it while turning the control through its range. For balance and fader functions, be sure the knob is pushed or pulled to engage those sections when exercising it.

The example above from a later radio is a little easier to demonstrate because it has its own circuit board, but the same principle applies.
--
Art Benstein near Baltimore