Williams 5505 PRR T1 Duplex 0-72 Steam Locomotive & Tender

I am not sure if this applies to your locomotive but a friend of mine had a Williams brass Duplex that had a similar issue jumping the 072 curves. I remember he realigned the curves and made sure the tracks were all level and flat. Also he minimized the gaps between tracks. That seamed to correct the problem. I have a  Williams Brass Big Boy ( 1989 vintage) that had that same issue with my 072  tubular track and after some track realignment it ran through the track  with no problems. 

Some lateral play of the wheels on big locos is normal to allow them to navigate curves.

What track type are you using?  Do you have any other articulated/duplex locos that go through these curves?  Have you checked for any of the wheel binding or being out of round?