The easiest thing to do is reverse the hot leads on the #2 and #3 lugs on each volume control. The #1 lug is usually soldered to ground on each volume control. This will reverse the circuit to the lever switch before going to the jack. You will have independent volumes for the bridge and neck pickup. Rewiring a ES-335 or any of the acoustic electric guitars can be quite difficult and should be done by an experienced repairman. It’s easy to get the parts out but can have you pulling your hair out trying to get them back in.

Never solder the controls through the “F” holes while the parts are loose inside. This is a sure way to burn the inside edges and top finish of the instrument. Believe it or not I have seen instruments where the player cut a hole in the back to make it easier to work on the controls. Please never do this! Some guitars are made to be worked on from the back but not Gibson acoustic electrics. The controls must be completely removed.

If you loosen a volume or tone control and need to get it back in the hole, try using a standard lead pencil and remove the eraser. It will fit through the mounting hole and provide a firm fit around the knurled shaft of the controls. You can pull the pots through and slip the washer and nut over the pencil shaft. After trying it a few times the job gets pretty easy.