I'm not sure Pro Gold will have any negative effect on your circuit board, it may be safer to leave it.
If you must try something, maybe circuit board cleaner from Radio Shack, alcohol or even Premier' (the LP cleaner in spray can that replaces Freon).
In any case, I would test on a spot near one corner with your preferred solvent saturated on a cotton swab to see if there is a reaction or damage.
You absolutely do not want to dissolve the coating on the circuit board or damage capacitors, trim pots or other sensitive parts trying to remove a bit of Pro Gold.
