Window sticks in up position
 

I did a search and can't seem to find a thread with this problem. After FINALLY figuring out my passenger side window problem was due to a kinked and broken wire I had good power windows on both sides...for a few days. My driver side window started acting up so I assumed it was having wire issues as well. I have figured out that the wires are fine but for some reason the window "sticks" in the up position. If I use an allen wrench and roll it down a tiny bit it works perfectly. I did notice that it takes a pretty good amount of pressure to get it to move initially but then it works fine. Any idea what is causing it to stick in the up position?
TIA

Bump...sorry
any idea why window would jam in the fully up position? Is there some sensor that turns the motor off when it's fully raised? I'm pretty sure it just stops when it hits the top of the window frame but maybe I'm wrong since I don't think my '8 cab had a window frame so how did it "know" to stop?