Hi Mads,
I (vaguely) a topic on BW1: a guy who used to do lot of cosmetics repair (Leslie…) did polish the glass – maybe with some sort of acid) where the black square is then painted it then use epoxy glue. The result was nice.
About epoxy glue not holding well: I glued the glass of a BS9000 with 2 components epoxy and it is still holding strong 3 years in vertical position and 3 years in horizontal hinges down. Moreover one hinge is lacking the spring which must put some more strain on the glue. Also glued many BS2500 glasses without issue. I would do the same if I needed again.
Cheers.
Edit: One more tip from the past:
