I bought a used Bachmann Pennsylvania 0-6-0 for my kids, but first try it doesn't smoke. I can smell the oil heating, but noticed some oil on the undercarriage of the engine. Otherwise the engine runs well. I'm thinking the oil tank is cracked, but am leary of opening it to check. Can I safely open it without parts coming loose inside, and is there a way to repair the tank, if that's the problem?