Very instructive John, thanks for sharing. A perfect example of why I've been saying our locos should have:
- worm gear connected to the motor via universal joint (not pressed onto the motor shaft)
- a separate gearbox that clamps around the worm wheel
- a two-piece chassis with "bottom plate"
- removable wheel-axle-bearing assemblies
- segmented drive rods (if necessary to accommodate slight play in the bearings and chassis)
If the above were true, this would have been an easy job. More likely, it wouldn't have failed in the first place. This recommended approach isn't new, and doesn't require any major engineering breakthroughs. Lionel should have copied 1960s US Hobbies, or even early '90s Williams and Weaver brass, not K-Line!
The J3a Hudson guys are grousing about mix-and-match driving wheels, or the lack thereof. If the wheels and axles dropped out of the chassis (and assuming extra parts were available for sale), they could use any combo they want. But that would constitute modelling, not collecting. Oops, sorry! 
