I can't recall if it was a 2-4-2 or a 4-4-2 that came with the Scout starter set a few years ago. That engine (mine at least) would bind on most curves and ended up being a small spring that looks like it was meant to recenter the pilot that was a bit too stiff. Since one purpose of the rails is to steer the train, I don't understand the need for the spring and the engine hasn't had any problems since its removal.
Hope this helps,
J White