hi found the problem its the two jockey pulley's are worn that tighten the drive belt. cheepest place i found is below.
to get to them take off top then control pannel then bottom plactic bit then the front. only took about 15 mins.
http://www.espares.co.uk/part/tumble-dryers/hotpoint/tl61p/p/1088/808/0/503972/102941/jockey-pulley.html
Gavin Jacques, September 2008