It will 'rock and roll' if the load is unbalanced. This occasionally happens but if it as happening all the time then the two shock absorber struts under the drum could have given up the ghost.
Go to www.espares.co.uk for the parts and whilst there click on the 'Advice Centre'. They probably have a video showing how to replace these parts.
GB in Wales
February 2013
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix washing machines.