The bearing kit can be bought on e-Bay
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=200367708884
Cost is 16.48
You have to split the machine casing and remove the tub completely from the machine. It's a fairly big job and took me all day the last time I done it about 3 years ago. I'm just about to replace them again as it's starting to make a rumbling noise again. Last time I bought a complete rear tub complete with bearings (the tub is in two halfs) for about 90 quid from Zanussi as I was concerned the bearing housing might have been worn too. However it was okay and I now have a spare rear tub. I would recommend renewing the bearings as soon as they get noisy as if the bearing collapses (steel balls fall out of race and drum making a loud banging noise) the inner ring of the bearing gets stuck on the inner drum drive shaft and the outer gets stuck in the tub bearing housing making them more difficult to remove. I found that one of the hardest things about the job was getting the seal between the drum and the door back on!
I have exploded views of the machine in pdf format if they are any help.
Stan
November 2009