Lionel Pennsy Flyer 0-8-0

That is a LITTLE motor!  You might check to see whether Lionel substituted a larger motor in a later model of your switcher.  I know a lot of folks have upgraded their Polar Express set locos with the larger motor from later production runs.  The Berkshire Jr started life with that same flat-sided can motor, so perhaps the mounting interface for the larger motor is compatible with the switchers, too.

Since torque is transferred through the side rods, you might order a new set of those as well.  The holes could be worn from heavy use.

It's great that you can replace the number four wheelset.  Even if you just freshen your loco with stock parts, you could reasonably expect another 11 years out of it.  As your kids get older they may run it at more realistic speeds.  Switching to slightly wider curves would also reduce the wear-and-tear.  Good luck!

@Ted S posted:

I know a lot of folks have upgraded their Polar Express set locos with the larger motor from later production runs.

Are you sure about that?? The upgrade is buying a loco with a larger motor as the smaller ones can't be swapped...

Is there any place online with a catalog of Lionel loco and rolling stock exploded diagrams and part numbers? Or is it all in book form? I imagine with all of the changes and iterations over the years that the Lionel P/N list must be staggering. I've seen diagram excerpts here for various higher end models, but if anyone can point me to a link for the late nights/early 2010ish  0-8-0 generic USRA "ish" switcher so I can match parts vs online sellers , I'd be grateful.

I'll check those side rods for excessive slop. It does have the Lionel "basic" side rods, not the fancier running gear. I've kept those lightly oiled and the hex screws for them are solid and tight. Amazingly my super glued wheelset (see my 2012 post ) is also still intact! We're dedicated to Fasttrack, so it's always going to have O-36 curves at most.

The kid who received this is now of working age and not as much of a fan, but his little siblings, while running it slower, have much larger & heavier consists behind it. I've picked up another RMT to assist in sharing these difficult "small engineer" duties so the old Lionel lasts a bit longer.

It's just the nature of the beast. Those cheap little motors just don't last. The worm gear on the motor always stripes out. Nothing you have done. Over the years I have replaced 40-50 motors for the same reason, striped worm gear. Poor design.

@Jeff T posted:

Are you sure about that?? The upgrade is buying a loco with a larger motor as the smaller ones can't be swapped...

I'm sorry if I'm mis-remembering.  I don't want to spread misinformation.  If it's not the Polar Express Berkshire Jr., then I must be thinking of the Hogwarts loco (4-6-0) that started out with a small motor and later Lionel installed a bigger one.

I know that Forumites have inquired about upgrades, and I thought some folks upgraded one of them.  And yes, given a choice it would be better to buy one of the later ones factory-equipped with the larger motor.

If the motor stripped the worm, it’s probably not the motor that is the problem.

I would look for binding in the drive wheels, especially the side rods. Barring any drag there, it might have just been too much load for the gear train, or maybe operating it too long without lubrication. As the metals heat up over and over, they weaken.