Erm...the drive shaft comes through the hub bearings and there is then a pin, referred to as a 'roll pin' i believe that goes through a hole in the drive shaft. This pin then engages in the wheel to provide the drive transfer to the wheel?
Might have just answered my own question actually:
http://www.sosidge.com/?p=418
3/4 the way down this guy mentions the same problem and has replaced them with 'nortech' drive pins, who are Nortech?