Update:
As it turns out , this mod wasn't nearly as difficult as I thought it would be. I don't have anything but the basic home-owners type of tools (so I wasn't sure I'd even be able to do this), but it's done.
Here are all the tools used:
The screwdriver was adequate for removing the insulated wheels. The large "Irwin" clamp was good enough to press the new insulated wheel onto the axle; I had to use the "C" clamp to press on the metal wheel. The hemostat was to ensure the axle gear stayed (more or less) centered while I pressed the new wheels on; the hammer and punch I used to knock out the axle from the replacement metal wheel.
I now have a spare set of wheels, still attached to the donor truck you see here; the caliper was for setting the wheel gauge, and the (2) loose wheels are the ones I took off the unit. I thought they were plastic, but now I think they might be metal, grooved for the "Pullmore" traction tires (?)
So there you have it; this odd example (made from several models, I'd guess), now has (8) metal wheels, no traction tires and picks up current from (2) wheels and the pick-up shoe from each rail. Much better. 
As always, thanks for sticking with me on this project...
Mark in Oregon
