I work at a fiberglass repair shop if the cloth is lifted anywhere try to get a putty knife under it and with a heat gun heat in front of your knife and see if you can get it to come off in strips. If this doesnt work you will be forced to sand through it with 60 or 80 grit ROS. Epoxy will stick to any polyester or vinylester but not the other way around, although you can get polyester to stick to epoxy with a vinylester barrier coat, silly, silly stuff. Anyway sanding lightly with 80 grit will create a mechanical bond to glass to. Hope this helps Good luck