Ur quattro starter fault?

["Jim Haseltine" <Jim@ur-q.freeserve.co.uk>]

My Ur-q got itself flatbedded today. There I was, passing a line of slower
vehicles, revs at about 6000, pulled back into the traffic stream and with a
rattle the engine cut. Coasted for about half a mile until I found somewhere
to pull off the road. The radiator fan was working and the temperature gauge
was showing at 2 segments above 'N' (probably 'cos the engine had been
working hard for a while before it stopped). Tried to restart but all that
happened was that the starter motor spun, the starter drive didn't engage
the ringgear so the engine didn't turn over. Had to call recovery and was
flatbedded home.

The situation hasn't changed, starter spins but the engine doesn't move.
I've swapped the starter with the one from the 81 and that does exactly the
same thing so I figure that its a supply problem - but what is it?

Jim Haseltine