I just did a little scraping under my coupe and found that my Fein multi-master.....
Same here; good results with a vibration cutting tool combined with a (not very sharp) knife attachment.
It is the kind that carpeting people have to cut glued carpets free from the floor.
It kind a melts the material at the edge of the tip, going like a warm knife through butter. The residual tiny bit of material flew off with a wire brush on a drill.