Yesterday evening I returned to my car and found the passenger side rear window open about 1 inch. It had been raining and a small amount of water had gotten in, but did not appear to be enough to cause significant damage. I tried the window up button but it had no effect. I then tried the window down button and the window literally fell into the door. It would not move after that. I called Tesla and they planned to send a ranger the next day to fix it. I drove home with the window all the way down (not a pleasant way to cover 30 miles on the interstate) and cut a piece of cardboard to fill in the window for the next day.
Today the Tesla Ranger came to my workplace to fix the window. Apparently there is a bracket that is prone to breakage that allowed the window to come out of the track. He even said he would replace the same bracket with a reinforced one on the drivers side window to prevent the same thing from occurring again. I was very pleased with the service. He even gave me a set of floor mats.
On the way home today, I noticed a slight wind noise from the drivers side rear window, as if it was barely open. I tried "window up", but it made no difference. I tried "window down" and the window fell into the door. The same problem had occurred again. When I got home, I was able to pull the window up to its normal position. It wouldn't stay there by itself, but some packing tape is holding it just fine. The Ranger is coming back tomorrow.
I don't know if this is a common problem or I just have bad luck. If this happens to you, pulling the window glass back into position is much easier and results in a better seal than making a cardboard template. I wish I had thought of it the first time.
It is not pretty, but it works. If the ranger wasn't coming tomorrow, I would have spent more time on making the tape look better. This "fix" took about 1 minute.