Cantelevering is not a good idea on a lift most times. Shoring up both left and right sides of the lift with another braced piece of metal will go a long way.
The clicking may be alleviated by using rubber bands to assist the lift. As you lift higher and the lift get vertical, the weight distribution changes a bit. The first joint where you have the big motors carries a bunch of weight. You could also be getting some torsional twist on those points as you lift up and that coupled with the cantelevering could be causing some separation of the gears.
Remember the gear touch point is pretty small. It’s just along the face of the gear teeth. You need good contact there to transfer the force.