Your brushes/bushes may be stuck or used up. Take to lid off (unplug first!!!) there are two brushes on either side of the motor that can slide out, don't be scared of looking and you can order more on ebay!!!
Donna
October 2007
Could be any reason at all such as a water leak from the door seal getting on the electrics or a million other things but I would go for the heater being blown so check this first.