I had the same problem with my zanussi tc 470. I bought a new belt however couldn't work out how to fit it tightly. After dismantling much of the machine and much head scratching I finally decided to look for some advice! I have just followed the advice and pictures on http://www.wikihow.com/Replace-a-Broken-Drive-Belt-in-a-Clothes-Dryer
and I now have a fully working machine.
Thanks for the advice, pauline.
Robin, January 2007