When replacing the vent rubbers I've both drilled-out the hinge on the frame and the pivot rivet. I think removing the hinge from the outer frame is easier and is an easy repair w/ pop rivets. If you drill the pivot rivet it's a bit challenging to buck the replacement rivet.
Be real careful when you remove the spring-loaded nut on the lower post. Put some Blaster on it in advance as that bolt is only brazed onto the glass frame and a bit brittle after 50 years.