Hey Tubedude,
Like Christiaan mentioned, if they have a lot of wear on them there may not be a lot you can do but change them out. Most good potentiometers are sealed, however I have been able to spray tuner cleaner down the shafts and let it soak for a while if there is no access in the body. Then you must rotate or slide them vigorously to clean the wipers and the resistor pad.
the other thing I have done is actually removed the pots from the circuit and soaked them in tuner cleaner for a while"
You may want to try cleaning them first before you replace them?
Best wishes
Pier