I just replaced my gearbox. There is a youtube video that gives you step by step instructions. I drew a diagram of the bottom of the cart on a piece of cardboard. After I took the screws out, I place them onto the diagram. There is an electrical box inside. I would suggest you take a picture of the wiring or mark each wire. Once you remove the cover, there are about four screws that hold the gearbox on. Remove the gearbox. Remove the two motors from the old gearbox and assemble them on to the new gearbox. Then assemble in reverse order. Having a screwdriver that is magnetized or having a magnet may help removing some of the screws.