Here is a tip i used to remove the vent glass from the frame. I picked up a heat gun from Home Depot for 10 bucks in the paint dept. The same gun in the tool section was 19.99. Anyway I turned the gun on high and played the heat around the frame, inside and out. In just a few moments the tar softened and I just pulled the old glass out. Useing the gun and a screwdriver in tandem I scooped out most of the remaining setting tape. A few minutes with a solvent and the frame was clean as a whistle.
