There are a number of products available to clean pots and faders. One is 99% Isopropyl. DeOxit D5 or one of the other Cramolin brand pot cleaners works well. Also, Tri Chem makes/made a plastic safe contact cleaner for pots and there's Blue Shower by Techspray, L.P.
Pull the plastic knobs up first. Spray onto a cotton swab and let it drip down the shaft. Work the pot to work in the cleaner.
Canned air is good for blowing dust off and getting the cleaner to dry quickly.