To do it properly, open the cavity where the pots are and spray contact cleaner (Servisol or another brand, not WD-40 into the opening of the pot. This is the base where the wires are atached. Then rotate the pot a few times and see if the scatchiness reduces. If it does then repeat and the problem should go away. If it doesn't then you will need to replace the pot/s.
You can try Luther, or Sim Lim if he has none left.
WD-40 is more of a lubricant than a cleaner. Very very bad idea.
GC and Davis sells Allparts pots and Swee Lee has Dimarzio ones if i'm not wrong. Make sure you get audio taper and not linear taper ones.
If you're replacing the pot, take the chance to experiment with different pot values and stuff like a treble bleed network or a full sweep coil tap. You may find some new sounds and versatility you never had.
There is a shop in Sim Lim Tower (not Sim Lim Square) on the third floor if I remember rightly called Silicon Electronics that sells Servisol switch cleaning lubricants. They also sell some sizes of pots in Audio and Linear Taper.