Hello,
Inclined to disagree with alexK. :bomb:
WD40 IS the stuff to use, you can use it on high voltage electrics (e.g. car ignition circuits) to stop them flashing over, it's a pretty good insulator.
The reason why I would shy away from contact cleaner is that it tends to de-grease what you spray it on. The tracks of pots are lubricated, if you remove that lube, they wear away pretty quickly. The WD (and some rapid wiggling) will tend to flush away the contaminant, but leave some grease.
When I used to work for a well respected guy fixing pro audio equipment, we used to see the results of contact cleaner on pots all the time. on a mixing desk it got expensive!
If the WD doesnt work after a few tries, then try contact cleaner / spray-isopropanol and re-grease the pot with a light NORMAL grease.
We used to have a phrase, "if it should move- apply WD40, if it shouldn't- apply evo-stik!"
Nig