I had trouble removing the glass cover - it would turn about one sixteenth of a turn and no more.
To get it off I got a cotton bud and soaked the end in 3-in-1 lubricating oil, then rubbed the end of the cotton bud around where the metal collar of the glass cover meets the roof of the oven (i.e. where it's stuck). I did this with both ends of the cotton bud in order to get a decent amount of oil on the surface.
Then a few forceful twists to and fro and I was able to free the bulb cover from the holder without shattering it.
NotNah
November 2020