[runner4fun]

I'm back-dating a 1983 SC coupe. I bought a new replacement windshield and managed to remove the rear view mirror button and the glue. (I'm installing an old style ceiling mount rear view mirror.) Now I find there is a round black sticker on the glass under where the button and glue were that was put there as a base for the glue presumably. Any ideas on how I get THAT off? I've tried goof-off, acetone, lacquer thinner. Nothing touches it. I can't even get a razor blade under the edge. Help, please.