Drivers window falls out of track, How to fix?

[Kenbo-Slice]

Hey guys, is this a common problem with these trucks? The drivers window falls out of the track once it gets about halfway down. I thought that the vent window was to blame, but I'm not sure. The weather stripping needs tp be replaced on the inside, but that can't be the only reason.....

I have power windows and the motors seem a little worn out and tired as well. I was going to replace them and thats when I saw how messed up the drivers side was. I'm just not sure as to why it's happening. Any ideas??