Just had this problem and managed to cure it by the following method.
1 turn dryer around to access rear
2 disconnect black drain hose at top end (it rotates to disconnect - this is how you would plum appliance in to a drain)
3 allow hose to rest at floor level in a container
4 run dryer - you may find some water comes out
5 return black hose to normal position
for us this fixed the problem
Julian, September 2008
