[Fisherdude]

The three golden rules about cleaning something you haven't cleaned before:

Start with weak cleaners, not strong ones. If it does the job, no need to go further.

Start small, not big. Do a little corner, not the whole thing all at once. See how it works.

Make that a little corner in the back, not the front.

And the "Oh, by the way" part: With dial glass lettering, don't start with anything containing more moisture than your breath, and don't start with anything more aggressive than a delicate touch with a tissue. Too many of us have cleaned the dial of an antique radio and ended up with a perfectly clean piece of naked glass.