generally slacken off the motor mounting bolts and refit the belt. Why did the belt fail though.....
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. Check for rusty spray around where the pulley shaft enters the outer drum - early indication of seal and bearing failure. Another method of checking is to remove the drive belt and rotate the drum by hand - there should be no noise, roughness or resistance to rotation.
Repair and service your own washing machine. Go to www.2ndwave.co.uk/manual.html
dannyboy
November 2008