this is how you fix an nes controller that has sticky buttons or doesn't do anything when buttons are pressed.
Step 1: Take It Apart
Get a small phillips head screw driver and take all six screws out of the back of the controller and take the back off and remove the board from it.,
Step 2: Sand It.
take fine grain sandpaper and lightly rub it on the contacts where all the buttons would press down on.
Step 3: Clean the Buttons
flip the buttons over and clean them off. i just used a damp paper towel.
Step 4: Put It Back Together and Your Done! You Will Notice a Great Difference When Playing Your Games! Have Fun!
you will notice a great difference when playing your games! have fun!