I had a strange problem and could not figure it out: the window would go down slowly, but I guess the motor had a hard time coming up. Since I am not so educated in mechanics I thought the obvious: regulator. Or the motor was going to the trash. A friend told me to try some good old wd40 on the sides, I mean generously. The issue seems to have gone away. My car is 103K miles ( x5 2003). So here is my question: is the regulator the one that breaks and the window "falls" down without support?