I have now fitted the door glass on both sides of the car, it was without doubt the worst job ever and I'll share my thoughts for anyone else that has to do this.
The alloy frames were in poor order, with lot's of deep pitting. I got a mini random orbital sander and started with p80 grit paper and gradually worked through the grades to p2000, then used a polishing compound
on a foam mop and finally metal polish and a sheepskin mop. The results are acceptable I think.
The biggest problem stemmed from the fact that both doors were new and I had no kind of guide, other that looking at photos and trying to remember the set up on previous cars.
I test fitted the frames before painting but should also have drilled all of the holes, cut the new rubbers and installed the glass as well. As it was, I needed to grind out the door moulding in various places, as the
frames were such a tight fit after painting. Also, the quarterlight rubber has an inner lip, which fits over a raised step on the door moulding, this fibreglass step was too thick and the rubber was incredibly difficult
to install and doesn't sit right on one side at the moment. I left the vertical rubber until last, once the quarterlight glass was installed I fitted 4mm wedges between the vertical sliding glass frame and the glass itself, this
left enough room to carefully push the rubber through the gap and seat it in place. The results are not perfect but pretty reasonable, plus I didn't break any glass, the alloy frames or scratch the paint.