hi,main cause of belts coming off is the drum bearing going,to test with door open see if you can lift the inner drum at the top part of drum with your fingers ,if there is more then 10mm lift your bearings have gone,a long job,if the drum can be opened,but alot of newer machines have the welded type ,that are scrap when bearings are shot,new around £ 140,thanks.
BILLTEC
November 2012