1968 Barracuda Rallye Dash gauge lenses removal

The original gauge lenses are scratched up, stained, and one of the decorative center pieces was broken off and lost before I got it. I got replacements, but need to figure out how to best remove the originals without damaging anything. I recall finding a guide somewhere but can't remember where or what it said. The originals are glued on with some kind of low temp plastic. I don't want to have to buy a whole new dash bezel because I took the wrong approach removing the originals. What's the best way to remove them?