Aparently you don't :shock:
Acording to the workshop manual if it's got play in it it should be returned under warranty, I read that somewhere.
Anyhoo, on topo there's a lilttle screw with a Hex head and a locknut. Adjust it inwards in small increments and check that the steering doesn't get tight spots anywhere in it's travel. This screw adjust the "mesh" of the roller wheel and the Worm, it's the only adjustmenbt I'm aware of that doesn't involve a strip down.