Okay, I'm not bashing the excellent finely detailed USA Trains Big Boy at all...Well it is too heavy but that's another topic. What I am bringing to attention here is a major manufacturing flaw that I discovered after running it for a few days. What it would do is short itself out electrically for no real reason. Sometimes it would short itself out when changing direction. The dang problem drove me crazy trying to figure it out.   Every drive wheel has a carbon brush rubbing against the backsi