The arm that attaches to the bottom of the window uses a pin with clip and special washer

It's a bit fiddly since you can't see it easily, mostly you'll be working by feel, the clip slides into a groove machined into the tip of the pin

There is a rectangular plastic bushing that slides in the window-bottom track, it fits over the pin first

Then the pin and bushing go through the track

Then there is a plastic slightly-conical flat washer with a metal star-shaped washer that fits over that

Then at the very tip of the pin - facing into the door, there is a spring-steel clip

I used a pick and a flathead screwdriver and a pair of needlenose pliers and a bit of cursing to get it out and back in

NOTE: the window drops after you pull out the pin, since nothing is holding it up - I put a small prybar in place to hold it up, but you could also use a piece of wood or whatever