I have had a scratchy volume pot on the bridge pickup on my ES335 for a month or so now and yesterday when practicing for BLIM3, sound was deteriorated and it dropped out once or twice.
I have not had the Gibson for long so was a bit nervous of playing around with it, To take it back to the music shop where I purchase it would be a round trip of 130 mile and probably a wasted day.
I knew the likely solution would be remove the knob and get some good switch cleaner down it, and give it a good twiddle. I already have an aerosol of switch cleaner. I looked around on YouTube and found a luthier who was servicing an ES335, and had done so in two parts. Well worth a look at if you have a similar style guitar.
The method for knob removal he shows is very simple, I followed his instructions using a clean duster, wrapped it tightly under the knob, then twisted duster tight and then pulled upward to to remove the knob. NOTE - I would recommend you hold the outside of the knob firm when tightening the duster so you do not strain the switch inside. It took me a 2 or 3 goes to get it right, but it works a treat. I did both volume pots while I was at it, squirting cleaner around the shaft allowing it to run down inside and then liberal pot twisting, NOTE:- Best to protect the guitar body and paint from the cleaner with an old cloth.
I tested it before I put the knobs back and was immediately amazed at how much nicer everything sounded. A job well worth doing on any electric guitar IMO.