As explained above all filler is not the same. Corvettes need a polyester filler so it will expand and contract at the same rate as the glass itself. The photo in post 10 shows the fender with filler applied. I don't know what type of filler is on the car, how thick it is or what evils it covers. It must be removed.
So how do you remove filler without damaging the glass any further. It's not as hard as you might think. This photo shows the tools you will need. A heat gun, wire brush, gloves and a dust mask. (I use a respirator but a dust mask will work.)
The heat gun I use is made by Milwaukee and turns our a good bit of heat, the air will easily burn your hand. The fine SS wire brush is made by Lincoln (welding).
It's available here, link: https://www.homedepot.com/p/Lincoln-...H581/100341129