I bought my 94 Altima used back in April with a problem that the previuos owner promised he would fix for me. unfortunately after months of him avoiding me it is still not fixed and now I am thinking of fixing it by myself. I have very limited knowledge of cars, but he said it is an easy replacement so I figured I would investigate. I do not know exactly what is wrong with the window, but I will give you all that I know and you might be able to piece together what the probable cause is.
The previous owner said that the problem could be fxed with a $10 item and it should take about 15 minutes to replace.
He said that the problem started when water got into the door mechanism.
When I first got the car, the window would neither go up or down. Since then I have gotten it to work twice, but after each time it would get stuck and would take a very long time, i.e. weeks, before I could get it to go back up. After the last time I did it which was in June, it has stayed down and refused to budge (which is why I need it fixed).
It is only the driver's side window; all other three windows function normally.

I was thinking it might be the motor shorted, but that is just a guess. I was hoping someone more knowledgable that I could figure out the problem from these symptoms and let me know if it is fixable on my own or if I should bring it in. Thanks so much!