This happened with our TD524. I think it may be linked to the fact your rear bearing is disintergrating. The bearing that was orignially fitted was replaced with a new part number 125 01 34 - 13/5 which could inidicate that they had a lot of issues with this part failing.
It is likely that you will need to replace this. Relatively easy job and the parts can be found at www.espares.co.uk costs about £6.00 and you might need a new front felt gasket.
Alan, October 2006
