Well! We've had a drive failure. Turns out we has the wrong sized rollers in the variator. One jammed and caused a bit of a mess. Damaged sliders and the variator drive bush. Another variator was fitted but the bike lost 19 mph worth of speed as a result.
Fortunately we managed to press the (now oval shaped) bush out of the fast variator. a good friend machined me a replacement bush. It took around two hours on the lathe to make the part, but its back together again.
A speed test saw an indicated 63 mph ( down hill of course )