My 2000 drivers side headlight will close then re-open about half way. I have replaced the stop, (head bumper), and that temporarily fixes the problem. It seems that the arm hits the stop with to much force and after about 5 cycles it cuts the stop and the problem resurfaces. I have previously replaced the gear in the motor with a brass one. The motor seems to rotate freely in each direction when not installed. Does the motor or arm have to be in a certain position when installing?