I am attempting to replace the rear quarter vent window seals on a 1937 Cadillac LaSalle. The procedure should be the same for Chevys and Buicks. I have the old weatherstripping out but I can't get the glass out. I would prefer not to remove the galss from its channel if at all possible. There are pivots at the top and the bottom and two corresponding holes in the new weatherstripping.

Is there any trick to getting this out and the new weatherstripping in? Is there a hidden pin or is there a chance something has rusted together. I don't want to drill any rivets out until I have to.

Thanks, Jay