I have an issue with two newly acquired Athearn Blue Box engines. They rock too far to the side. They always right themselves; they do not lean when standing. As far as I can tell, this is caused by a small king post plus the surface contact area on the truck bolsters and the frame where they contact. Other BB engines have a much larger area to contact. I would say this engine has a contact diameter around 5/16 inch whereas the regular Athearn BB is around one-half inch. Seems the frame is made of lighter material than the normal engine. In fact, I have wondered if this is actually a BB engine. Also, I have an SD9 which is the same way. Anyone ever see this before? The engine runs fine; I have just converted it to DCC. (Seems strange; just wonder if I am crazy.) Thanks.