Thanks John. I've the mechanism (below) just (just being the operative word), need some glass as specified in post 1, that I can insert into:

Wanted solution, a red glass as specified in post #1 to replace the yellow you all see in post 1 and in the first pic of this post:

I think I should be able to solve this little riddle with a beat up used 25a and a glass cutter but
I've no idea??