I cut the screens out my W111 coupe this week and they were the original 1962 parts. talk about hard!! . i have to shave the rubber seals down with a stanley knife to get the glass loose. it appears that when the car was assembled someone got carried away with the glue that holds the headliner up. It stuck the rubber in damned good for 50 years.
The originals had a grey mastic stuck around the lip of the aperture and when the glass was finally fitted,a small amount of black mastic was pushed into the gap between the rubber and the body to prevent water getting underneath.