there is no tension adjustment to the belt as it is what is called a strech belt! is the machine noisey? if it is then that may be why the belt came off in the first place.re if not then try to re fit the belt following these steps.
1:remove plug from mains!
2: remove lid 2 star screws on side.
3: remove the bottom rear inspection panel at rear of machine.
4: check that belt is in good order,put belt around the pully wheel(you will have to do this from the top) then then when it is on the pully wheel use a small cable tie to secuer it on this will hold it on.
4:going to the rear inspaction panel you will see the belt hanging down grab the belt and postion it on to the pully of the motor when you have done this open the door of machine and rotate the drum this should then pull the belt on you will hear it go on and you will also hear the small cable tie snap! this is no longer needed. hope this helps
darren., April 2005