I am working on a Bachmann 4-6-0 On30 made for the Hawthorne Villiage Collection, it has a split/cracked gear on the axle.  The motor just spins and doesn't move the axle gear...infact it is now free wheeling as the gear is loose from the axle...I need a replacement part...but the locomotive is not listed in the product list....also could use an isometric diagram of the loco....can any one help?