you could clean the prongs inside the cartridge with wd40. it wont conduct electricity and its actually a good cleaning solvent.Sometimes its simply just the cartridge that needs to be cleaned, but N64 and SNES with all those old cartridges, all thats inside is a circuit board... I gave my SNES to my dad work mate who is the electrician at his work to make it work again, so we'll see whats up.... hopefully it'll work cuz I just got Super Mario RPG for $27 lol. $10 less than the lowest price on Amazon