Oooops ... all superfluous now ... box is finished, or at least, the CD is, so I'm too late.
I've been told that the box failed due to .... wait for it ....
a 'missing roller bearing between the two main shaft halves'. The only thing keeping the whole shebang together was the baulk ring, which eventually wore out. It took 5000km to fail. At least, that's the distance done in my care.
What I find amazing, is the fact that through all that torture, there was never any associated noise. No whining, nada and no record of replacement in the service record book. I think myself lucky it never 'let go'.