BTW, I sorted the sun visor this morning. Drilling out the headless set screw wrecked the old thread as I expected and so I trapped the hole with a 1/4 UNF, drilled the visor's hole out to 6mm and bolted it up with an Allen head set screw which was the only 1/4 UNF that I had which was short enough / long enough to do the job. The PO had put a rubber strip along the bottom edge of the hatch door which I have removed to reveal a few rust patches along that bottom edge. I don't know what adhesive he used but it was the very bugg3r to remove! It looks repairable but I'm out of Kurust at the moment so it will have to wait.