My drivers window started getting slow and then started working intermittently so I replaced the motor. My first problem was that when the window got down to the bottom in the express mode, the motor did not turn off but ran on and made a really bad noise until I cancelled the express mode manually by bumping the up button. Having just escaped from inside the door and getting it all back together, I wasn't keen on getting right back into it again. Now, there are a couple positions as the window is going down where the same really bad noise happens and the window stops moving until I pull on the glass. I know I've got to go back inside but I have a question first. What is the mechanism that makes the motor turn off when the window gets to the bottom?