Jerry: Thanks for the response. I will try your dime-trick to re-check the wheel spacing again.
Actually the shorting occurs just as the "turning out" outer rail is about to enter the frog itself. I see burn spots on the rail just before the plastic area of the frog o the divergent route; I also see burn spots on the bottom of the straight-through portion of the frog itself. I verified that by dropping some gel super glue on it. Once it dried, I ran the cars through and the shorting was reduced a good amount, but still happened on at least one wheel set on one car.
I've also done some judicious grinding on the sides of both convergent rails next to the plastic areas of the frog to hopefully widen that gap somewhat. I've also modified the AM design as to the placement of the guardrails themselves as they really aren't where they should be "as delivered" IMO. See attached photos.
