I bought the replacement motor from a dealer and when I overhauled the old motor, bought the new plastic gear from the same dealer. I think there was a broken tooth or two. New motor fit just fine and yes, I did unplug the power first thing before doing any other work on the step unit. A wood block held the step in the deployed position so I could gain access to the wire harness and motor without the steps flopping around. Easy job and I still have a spare.