Reach into the drum through the door and grasp it firmly. Can you rock it to and fro? If you can then it is a bearing problem, which involves dismantling most of the machine, including the the inner and outer drums. Although not especially difficult it does take time and it depends on how much experience you have if you want to give it a go. The Haynes washing machine manual may be some help - although not really specific to your machine you'll get some useful tips.
John
June 2008