[Paul Philco322]

I only have one set an Airline that had that type of a glass, fortunately it was in fine shape. It may be that over the many years of it's existence that any little gap or spacer that was there has filled in, shrunk, rusted into oblivion. Have you tried carefully scraping along the inner corner of the ring to see if there is some type of a clue concealed to the naked eye. Perhaps that might assist in figuring a removal.

Your photos are good I magnified til I started to lose resolution and I see your point, do you have a source for replacement glass with similar shape?

Paul