This is why you don’t get electric motors in car windows. After 20 years, they quit working. Until I find the desire to fix the window (and I might not since it is faster up and down now) the following describes how I went about rigging it up.
The motor stopped working on my driver’s side window and I needed it to go down because I have no air conditioning. After taking out the old apparatus (cutting rivets out) I decided it easier to just jam something into the opening to hold the window up. This something turned out to be an “L” shaped piece of wood and it works great.
To use this instructable you should try to focus on the overall idea and less on the details. I am operating a '91 S-10 Blazer and, unfortunately for you, you probably are not. Your car probably has an opening of some sort near the window. If not, find a hole (or make one) and just jam something in there. It needs to be tight so it doesn't fall out while driving. No fun to have a window fall open at 60 mph in a rainstorm.
The "L" block was just a scrap of wood and after I cut it to length I just cut the notch out it was done. The partially open window configuration was not intended but turns out to be a nice benefit. The pictures show the "L" block used in two configurations and the partially open window. The other option is to not use the block and let the window be full open. I figured no pictures would be necessary there.
Here is a video of the window being operated.