This is what your motors look like. You may be a able to take them apart, clean and degrease them, if they are not rusted up. Clean the brushes, springs, and armature. Then lube the moving parts and try it. Sounds like a broken gear in the one with the window,free to move. The description by Art seems like the earlier style motors.

You may be able to make a drilling template based off of this picture. Looking at the motor in the center. Bolt hole measuremeets from the center pin of the gear are: 1 5/8" for hole across from the phillips screw, 1 3/8" for holes next to the Phillips screw.

Remove the Phillips screw and cover, you will see the gears inside the housing.