Robert, If you can get a plastic putty knife and start to stick it between the body and the rubber on the out side of the car to start with and work it around the seal a little at a time, be carful with the paint ,hence the "plastic putty knife".
Try to work it around the inside also . I cut the putty knife down and sharpened it also to get in deeper on the corners. Turn the regulator so it has pressure to open the windshield while your are working on it, but not to hard that you damage the gears.
You will get it open.......take your time ....it took a long time to get stuck shut so it may take a little while to get it open!!!
Ron