I’ve spent 3 hours trying to make the new windscreens seat solidly in the new gasket and have concluded that the gasket is mis-manufactured. The center divider portion of my late style gasket on the '53 is only 9/16" wide and the original was 3/4" wide. The effect is that there isn’t enough depth of rubber, and the glass slips out at the center. Additionally the pocket for the interior center trim piece doesn’t extend the full length and is only 1/4" wide between the flaps, compared to 1/2" on the original.
Does anyone know of a supplier for a well manufactured seal? This one came from SNG Barratt quite awhile back - probably at least 10 years. It’s nice consistency rubber, but the center section is just too narrow to hold the glass securely. I don’t know if all the replacement gaskets are from the same manufacturing source.