The motor slots in from the right hand side. Note that I have lightly greased the worm gear - exaggerated by the camera flash. All of the grease is in the bottom of the groove. I also applied a small amount of grease to the teeth of the red gears, and pushed the chassis, without the motor, around the track to distribute the grease. Too much grease here isn't as bad as too much oil, but moderation is still very important. At lest the grease doesn't fly all over the place. I used some silicon grease I had lying around.