The Xbox controller has a left and right trigger that can be used alongside the many buttons studding its surface. A design flaw can cause overenthusiastic use of the left trigger to damage the connection of an electrical contact inside of the controller, resulting in the left trigger no longer working. You can repair the connection so the trigger will again work. The repair will require a few hardware tools and you will need to have experience in using a desolder pump. Repairing the trigger on the Xbox controller will not void the warranty on the Xbox itself in any way.
Use the Phillips screwdriver to remove the screws from the back of the Xbox controller--the screws are on each side, at the top and at the bottom. Scrape off the warranty sticker on the back with the Phillips screwdriver. Remove the screw that is now revealed. Put the screws aside.
Lift the back part of the Xbox controller up off the front part. Put the back part aside.
Locate the vertical metal bracket with the three contacts on it that is to the right of the button control hole at the top left corner of the circuit board.
Use the Phillips jeweller’s screwdriver to scrape the trace wiring off from the centre contact on the metal bracket and over to a screw to the right of the contact. Desolder the trace wiring after you have scraped it with the desolder pump.
Use the Phillips jeweller’s screwdriver to scrape the trace wiring off from the bottom contact on the metal bracket and over to a screw to the left of the contact. Desolder the trace wiring after you have scraped it with the desolder pump.
Cut two 4" lengths of electric wire using the wire cutters. Remove 1/2" of insulation off the ends of the electric wires using the wire strippers.
Solder the end of one wire to the centre contact on the metal bracket. Solder the other end of the wire to the screw to the right of the centre contact.
Solder the end of the other wire to the bottom contact on the metal bracket. Solder the other end of the wire to the screw to the left of the centre contact. Let the solder cool for at least 30 seconds. Reassemble the Xbox controller.
Lightly draw on the trace wiring with a coloured pen for easy identification before scraping it.
Tampering with the controller will void the warranty. Scratching the wrong part of the circuit board can make it become defective.