Hi there i recently took mine apart to put on couplers and what i did was take the both screws off on the front and end so it would open like a book then the small one on top for the electricity then lay it on its side put the good motor it then the wheels with the shafts correctly then ever so gently take the other piece and lay it on top and move it around so it falls in place then hold each sides tightly so they dont fall then screw them in Its kind of tricky to put the screws it but it will work just have to get them through the second hole and dont tighten them to tight i just stripped mine and then test it out on your track.