So on my 08 GMC 2500hd (crew cab) the rear windows will go down but not up, unless you repeatedly pull up on the lever a bunch of times and eventually it will go up. When it does go up, it goes up at full speed, and doesn’t stop or hesitate. The problem is the same in both rear windows, but the rear right window switch works normally, and the rear left is affected by the problem

(picture wont upload, dammit kinja)

Now their could be two possible causes besides random part failure. The first most likely one is that the doors used to fill with water when it rains. The second is that when I replaced a door mirror, I pinched a wire or two when I put the bolts back in. I took the door apart, and wrapped the wires in electrical tape, and fixed that grounding problem, but maybe i broke a wire?

The problems i can think of are: broken regulator, broken switch, broken wire, electrical black magic.

Anyone have any insight?