Tumble dryers generally have two drive belts. One for the drum from the motor which is inside the casing and one for the fan which is external at the rear. The fan belts normally stretch, then slap around before falling off. Unplug from the mains. Remove shroud with screwdriver and replace with new belt stretching belt over pulley wheels. If internal drum belt then remove whatever cover you can and note current belt position. There is generally an idler wheel that is sprung to take up slack in the belt. Replace belt running it through idler wheel.
Replace all covers before reconnecting to electricity
Richard, June 2009
