Numisma

Hello. I recently got a 1988 Land Cruiser that my father purchased about 20 years ago. My grandfather has owned it for the last decade, and didn't take great care of it, and now it has been passed on to me. My dad and I have been working on it for a couple of weeks and have gotten it in much better shape. One big issue is with the driver's seat window. While up, it can easily be pushed down by hand, allowing anyone to easily get inside, which is obviously a problem. It also tends to lean to one side (left, if you are in the car), but that is because the gasket on that side is missing (we will replace that soon). We removed the inside of the door to look for any obvious problems, but can't find any. Does anyone know how to keep the window up? I should add that the windows are manual, with a crank.
Thanks in advance!