I bought a set a couple of weeks ago, and i am having some problems with the switches. I am having problem when i am turning of the main line. When it turns the engine goes over the switch fine. But the first and second car always get re-routed to go straight . In other words the rim slides over and catches the peice of plastic that makes the train go staraight instead of turning. if someone could tell me a way to fix this that would be great. Thanx :-