urgent help needed with an indesit W1B111?

My machine does a normal wash cycle but while doing this there is a loud clunking noise like there is something loose in the drum and also the belt keeps slipping off when i put the belt back on the wheel on the back of the drum is loosened for some reason can anybody help with this issue as i really need my washing machine to be working or if someone could tell me how to get the drum out so i get a better look inside then please do so

Many thanks

Desperate householder
December 2010