I found a Bachmann 4-8-4 numbered 6005 from a packed away box when my kids were young. I think it is from the 1990's and tried running it. It ran good for a few days and actually still smoked. Then the drive gear locked up and will not move. I tried googling the loco to find a parts list or an instruction manual to troubleshoot or disassemble and had no luck. I tried Bachmanns web site and had no luck. Any help?