I didn't say this before, but my postulation is based on experience. (Just didn't want to write all this out, before.)
When I got my first truck, (The '89), the windows didn't work at all. I took the motors out and rebuilt them. Needed new brushes. I had to buy bigger brushes and "machine" those down to the right shape and size with a file.
That was the motor itself. As for the plastic bushings, yeah, mine were chewed up. I put, I think, 3, 10mm nuts in there instead of the bushings, and it worked perfectly.
Ok, so got those running again.
Now I had the same problem described in the OP.
The same thought came to me, on my own. Seems like when it bottoms out, it gets stuck. I wonder if it is over extending.
I found that if the door panel was off, and the window got stuck in the down position, I could put my hand under the bottom of the window, give it a quick nudge, and it would roll up again.
So, from that point on, if I remembered not to let the window go completely down to the bottom, it never had a problem with getting stuck again.
I intended to someday drill a hole somewhere so I could put a bolt in, that would prevent the window from going all the way down. Or maybe cut some wood to put below the window, inside the door, to let the window go almost all the way down, but not all the way.
But I got the newer truck and have been working on this one instead, ever since.