What is wrong with my tumble dryer?

I have a Zanussi TC481 which smelled of burning so I pulled it out to check for fluff etc. When I switched it on again there is now a dull thud every time the drum rotates. When I rotate the drum manually you can still hear the dull thud and it feels as if something is catching.

Has any one got any idea what the problem might be?
We have never tried to repair anything like this before but my husband is quite handy so perhaps I have nothing to lose. Do you think this is worth repairing or should I just buy a new one?