A recent rather silly problem for me -- on a rather expansive fastrack layout that comes and goes, I decided to hold it all together with small paper binder clips. I dutifully stuck them on between just about every track section. And then beyond the seeming standard fastrack connectivity issues I kept getting these shorts -- the train would run, then not -- jiggle here, crimp the ends there -- then it would be ok for a bit, then suddenly not.
It was maddeningly rather random ...
Then I realized I'd inadvertently put clips in a couple of places across power and ground. It really just came down to the way they clips were placed, many with me just putting them in without really looking since I'd put the track down first, and the length or shape of the handles on some clips which allowed it to occur.
Anyway... probably nothing to do with your problem but its the kind of issue that can cause one to very nearly throw it all in the trash... or at least feel like it.
