That is a baby drier?. If so you have to unscrew the fan at the back. There is a spireclip on this to stop it unwinding in use. Obviously you will not know this untill you undo the threehundred and sixty two screws that secure the rear air duct in position. Having removed said clip and duct, remove base plate, grip motor shaft and undo fan. Now you can remove rear panel,drum whatever!. Replace drum which u have taken out cos it's fun, wrap belt around it and motor shaft. refit back panel. fit fan 'n' cover, Relax with a job well done.
Ric, January 2005