Pop-out window removal help

I have a 73 Duster, the side pop-out glass assemblies are removed from car & I need to take the glass out of the frames to clean them & install new weatherstripping & all. My question is, how do I go about removing the pop-out glass from the frame assemblies? It looks to me like there are factory rivets at the front of the vertical part of the frame assemblies that need to be removed to take the leading edge of the window frame off, then I'll have access to the glass to slide it out (Maybe?) of the rest of the frame. Am I missing something or is this correct for disassembling them? The weatherstripping looks like it won't come out or go back in without doing this. I surely don't want to destroy ANYTHING, so I need someone who has done this before for their help. I'll have other questions, I'm sure, as I move along on this project. Thanks, in advance, for helping.