A lot of people have had this problem, myself included. One of the ways to fix it is to loosen the nut on the motor. It sounds stupid, but it works. I don't have a picture handy, but there are probably some in the archives. I'll try to explain it. You take the dome light console off and the motor assembly is right under it. On the right side of it, you'll see a cylindrical piece of metal, maybe an inch or two in diameter; this is the motor. You should see a nut on the end of the motor. Try loosening that nut a tiny bit and see if it fixes your problem. I did this and it worked for me.