Instructions
Tape up the vents and cartridge slot on the SNES console, then spray with all-purpose cleaner or vinegar-based cleaner. This cleaner can be sprayed directly onto the controllers and cartridge surfaces as well, as long as you allow them to dry before attempting to play.
Wipe clean with a soft cloth or paper towel. If the system is yellowing with age, spray the cleaner on the console, then let the console sit for an hour or so in order to allow the stains to lift off the case.
Dip a cotton swab into rubbing alcohol and swipe along the copper contacts on the cartridge. If there is thick dirt or grime stuck to the contacts, use a toothpick to dislodge the debris. Repeat swiping the moistened q-tip over the contacts until no dirt comes off on a fresh cotton swab.