It could be just a lead, check your lead heads and inserts are clean.
Check along your leads and wires for any obvious kinks / tight bends / cuts / nicks / something sitting down on it or any damage to the wires.
It could be there is another electrical device nearby interfering at a electromagnetic level.
It could be just the dials / knobs need taking off and cleaning in behind. the pickups, you may not need to remove them just spray with electronic cleaner
this stuff is great for lots of different electrical cleaning problems.