Actually, on reflection, I noticed that the direct drive rotor seems heavily recessed into part of the moulding in the back of the wash tub, so I am wondering if the clearance between the tub and the drum spider is unusually narrow.
Perhaps corrosion to the drum spider during the two years the machine was in storage has caused the spider to swell and bind against the tub rear wall. Removing the rotor would free up the shaft, allowing the drum to turn, So perhaps this is a tub-related issue rather than motor issue after all.
If anyone else has experience of this issue that would be great to know.