Researched this problem on mine a few years ago and came up with a part number from NAPA BK6551395, other parts stores also have them you could cross reference this number and get it. The cost was around $50. If I remember correctly it is a motor from a front driver side door on a 96 or so Ford Taurus. The parts store was a lot cheaper than the dealer. If I had to purchase from the dealer it would of been better to buy the whole step assembly. Mine has not completely stopped yet, so I have not actually did the change yet. When it does though I will only change the motor. There was a lot of info on the net about doing this change, but I can't remember where it was.