Yep - and it looks like I'll be needing a new belt.
Measured PE using Pempro and applied a curve, +1.5, -1.8 in the end which is pretty good, but the end result is still moving around by on average 1 pixel. I've gained some accuracy, which is a good result I think.
On the negative side the RA error has risen a little bit, but on the plus side at least the stars are less eggy and more round
I think when the new belts come I'll install them without removing the scope. That thing is heavy and needs safety gear to lift it properly
BTW - for any PMX owners out there I'm happy to order some spare belts and get some spare motor screws and send them around the place (for cost of postage and parts). Assuming that these belts come soon, it will have been a smooth transaction.