I got some rubber molding adhesive on the drivers side window and now cannot take it off. I do not want to scratch it with anything unknown because it is a numbers matching window. The hardened drip has been reduced to a very thin layer by applying Goo Off and various other adhesive removers. Yet, ultimately, what remains of the stain, is still there and cannot be wiped off. Even after many attempts. Any advice on what solvent to use without damaging the glass. And yes, I have carefully tried, on several attempts a razor blade with no success. Thanks in advance.