check why the belt has come off - indication of bearing failure.
Check for bearing failure by seeing if there is any vertical movement between the moving stainless drum and the fixed outer drum. There should be no vertical movement between them - if there is the bearings have failed and will soon collapse. Changing bearings is an involved job, only attempt if you are mechanically competent.
Repair and service your own washing machine. Go to www.2ndwave.co.uk/manual.html
dannyboy, November 2008