I cheated a bit and opened mine up. When you do that you can remove the circtuiboard, then manually extend the ball prong thingyjig by moving the wormwheel so that it's easier to fit. Once in place, you can roll it back a bit, then replace the circuitboard.
Sounds like a faf, but really it takes seconds. Before doing this cunning little workaround, I think I had spent about 30 mins of swearing and failing to fit them. Give it a go.