i have a bout a half dozen NES controllers in various working order, with two i use daily. they began to 'rogue flip" as i call it (flip a piece twice instead of once when i push a button), or stick when releasing the d-pad which is began to mess up my games. i looked online on how to clean them and followed the simple instructions found there. i used dish soap, as suggested, to clean the plastic components but never found anything to clean the electric connectors. anyone know anything that will clean them but won't corrode or damage them? i can't find an answer online- instead if find companies trying to sell me cleaner products. is there anything i can use that doesn't need to be special ordered? also, how do you know when a controller is dirty vs. when it is actually malfunctioning irreparably? thanks!