There is no easy way of doing this, as you need to get the belt over the drum, which sits on 2 bearings at the front of the machine, and on a shaft with bearing, through the rear.
You also have to remove the blower housing and blower for the condenser on the motor shaft too, as the pulley for the belt is midway down the shaft, and you will need to get the belt over the end of the shaft.
In the end practically I took the whole back off the machine, to get the belt over the rear drum shaft, which on mine is riveted on.
The whole operation took 2-3 hours.
If you have a machine where the rear drum shaft is bolted on, you may be able to remove the shaft, get the belt over the drum, then re-insert the shaft.
I'd also consider replacing the 2 belt tensioning pulleys while you're about it. They're about £8 each. Usually they start to wear out, then they affect the belt.
While the machine is in bits, Id also clean it out with a hoover, and examine the two bearings on the front of the drum. These are only nylon bushes which hold up the front lip of the drum, these are about £5 each.
All these bits are a pig to install, so there is a benefit to doing any required, or soon to be required work at the one time.
Barry, October 2009