I have an Overland Limited 4-8-4 with bad drive gear/axel/Drive wheel.  How do I repair the slipping part.  Gear is slipping on the axel.  The fiber gear is worn on the mid where it joins the axel.  What could be done to fix this problem?   HELP Do I have to replace the whole four Main drive wheels?  Are the drive wheels for most of the series the same? Ex: any 4-8-4 or 4-6-4 Hudson the same size?  What could be done to fix the problem.  Second, I need to know if Bachmann motors are of the ONE amp. max current type.  Help from anybody.  Thanks.  TK