You don't have to remove the front panel. The meter shield can be
removed from the rear. Once you get it off, use the correct size
spintite and remove the meter mounting nuts and lockwashers. Pull the
meter out the front and disassemble the case. The glass retaining
collar has probably slipped back and is no longer securing the glass.
Once you remove the meter movement, have a look see if that's the case.
If the ring is loose and won't secure the glass, you can use a couple
of drops of super glue on the inside lip of the meter case and drop in
the glass. Then slide the retaining ring in. If the ring is very
loose, one can deform the inside lip just a bit at one point to provide
some tension. The only thing to be careful of is to make sure the
zero-set pin on the case aligns with the zero-set loop on the movement,
itself, when re-inserting it.

Bob Spooner wrote:
I have a Viking II that the glass in the meter came loose. I'd rather not
disassemble the front panel (since it looks to be a lot of work) to remove
the meter which is behind a RF proof shield, so I'm thinking of just gluing
the glass in a few spots. What would be good for making the glass stick to
the meter case?

73, Bob AD3K