I have the complete car set as well. The cars are beautiful, however they are not made to work on 072 curves or switches.
When the cars where first released I had no issue with ONE car taking these turns but couple another on and the fun began.
First off I have notice that the details of the underbody do not like DZ1000 switch machines and their large screw heads. They even seem to pick the switch springs.
I have never been able to get this set to traverse over 072 curves. Thus I only run them on my upper deck with a minimum of 096, and I still have issues. I have adjusted the draw bars and removed the air hose details, however this lead to other issues.
Mostly unwanted uncoupling. S curves are a curse, even on 096 the trucks and couplers will uncouple, and the inside of the trucks hit the car bodies and will cause a derailment.
I use the same electrical tape fix for droopy coupler tacks.
The dome cars seem to be my most aggravation. If you do find a fix, I will be listening. However, grinding away details, which I did not want to do, may be our only hope.
