May I suggest that you also look at the track spikes where the black rails and silver rails are in close proximity? I spent considerable time trying to locate a short in a stretch of track and narrowed it to the crossover. I think that over time one of the spikes in the crossover moved enough to cause a short between the rails. I actually had to use a magnifying glass to see it. Just a thought.
Thanks, we will take a close look tomorrow, Sunday.