resolution, so far:
I took the door panel off... took the following loose or out: three screws up at the top, the two big screw bolts inside behind the panel, and the ones at the end of the door that holds the bracket for the rubber seal...
Then! I did some wiggling around with the vent window frame and the glass closed much easier. Then I tightened it back up and still had some issues... so, I started thinking with the new seals, everything is a lot tighter, with less slack or movement.
I played around with the top three screws that go through the top of the door into the vent window assembly... then snugged up the two in the door behind the panel.
Then... everything else and put it all back together.
I lubed up the regulator with some PB Blaster and so far, so good.
-W