look at this on Ebay or help
http://www.ebay.co.uk/itm/BELT-FITS-ELECTROLUX-TUMBLE-DRYER-NEW-BELT-WHEEL-1975h7-1258288107-/200665534534?pt=UK_Irons_Presses&hash=item2eb8991046
CK, December 2013
push the motor as far as it will go inward then fit the belt around the drum and motor shaft.now pull the motor back towards you and attach spring from motor to the plastic base.Job done and tensioned