'63 Dart wagon rear door glass.

"63 Dart 170 wagon. Wanting to replace glass run channels. I followed the service manual instructions for removing the rear door glass. The glass is free but can't get it out. The manual says to lift glass up and out of the door. The glass is tightly held by the run channel. Well, up and out sounds so easy but even after loosening both front and rear metal channels and moving them as far as I could, can't get the glass out of the channels. Also tried to rotate the glass but couldn't do that either. Anybody have some advice? There must be some trick here.

Thanks for any help.
Jerry in Denver