Things You'll Need
Instructions
If your controller is plugged in to your GameCube or your Wii, unplug it from the socket on the unit.
Place the controller face down on a table or desk.
Press the battery compartment cover latch down and remove the cover from the back of the controller. Then remove the batteries from the compartment.
Use your Phillips screwdriver to remove the four exposed screws on the back of the controller and then remove the single screw located on the interior of the battery compartment.
Lift the back half of the controller from the front but don't separate them too far as they are still connected via a circuit wire.
Lift the green circuit board out of the front half of the controller and set it and the back half aside. The controller buttons will now be visible in the front half of the controller.
Remove the rubber pads from the back of the controllers and locate any faulty buttons. Fit them properly in their compartments to ensure they work properly. If they are dirty you can clean them with a microfiber cloth and water.
Reassemble your GameCube controller in the reverse order you took it apart and it should work perfectly.