Looks all right on the outside, but trust me, it's nasty.
So, your Super Nintendo controllers have been sitting in the basement. They've been gathering dust and something might or might not be living on or inside them. Time to break out another how-to!
This controller, purchased with an SNES lot at Goodwill, had a left shoulder button that was near impossible to press. Something spilled on and inside it had fused the button in place. It'll make a fine candidate for the oft-searched SNES controller cleaning guide.
Remove the five screws holding the controller together.
First, flip the controller over and remove the five screws. They're easy to find, and none are hidden or obscured, so have at it. You'll need a 1/8" precision screwdriver for this, but most tool sets have one.
Back removed, but the shoulder button is still stuck in there. Is that honey?
Pull the back off and set it aside. Be careful when removing the shoulder buttons, as there are two metal rods holding them in place and allowing them to swivel. Set these aside.
The aforementioned metal rods, above.
Unsnake the cable and pull the board out of the controller.
Pull out the button pads and set them aside. Remove the plastic buttons.
Sudsy Buttons - hey, that could be the title of a Shirley Temple movie. Ask your parents.
Allow the buttons to soak in a bowl of soapy water while you get started on the button pads. The button pads can be cleaned with rubbing alcohol and cotton swabs, but do so carefully - if the pads come loose from the plastic, you'll need a new controller.
Clean this, too.
If the controller was a spill victim, make sure that there is nothing sticky on the circuit board. If there is, clean it up with rubbing alcohol. If not, see all of the little black pads where the buttons and D-pad should be? Clean those up with rubbing alcohol and a cotton swab. Don't forget the angled pads where the shoulder buttons connect.
And the case - eww.
Now, on to the case. The case doesn't usually need a lot of cleaning, but if it does, do so with soap and water, not rubbing alcohol. Rubbing alcohol can make the plastic cloudy, and occasionally makes the ink run.
This particular controller was so nasty I had to soak it in soapy water, too - it's safe to do so if you need to.
A clean controller.
Now that your case and buttons have been scrubbed clean, set them on a paper towel to drain and dry. Be sure that they are fully dried before reassembling; water in a plugged-in controller can fry it.
Button, button, who's got the button?
Dry yet? Good. Now put the buttons back where they go. You can see the locations identified with "Lavender" and "Purple" as well as the button colors for other regions, green, yellow, red, and blue. For a US controller, you only need the two. Even the R and L locations are labeled. Insert the rods into the holes and slide the shoulder buttons over them.
Put the pads back in, lining them up with the guides provided. Make sure that the black pads are facing up.
Put the board back in, lining it up with the guides - if you need a refresher on how the cord is wrapped, see the above image.
Done! Look how clean!
Put the back of the case in place, screw it back together, and you're done! Enjoy your nice, like new, hopefully not sticky Super Nintendo controller!