Can anyone tell me how to stop the magnet casing spinning? When reasembled and put back on the bike the central part that you attach the light electrical wires spins with the rest of the wheel unless you put your finger on it to stop it. Happy I have got all the correct bits for re assembly. There doesnt appear to be any lock washer or anything to stop it spinning. Dumbfounded! If you know the answer, please share it, thanks