you can tell which car is causing issues because that car and the ones trailing door's will fail to open. Pull the first car with door issues and the remainder should work. My initial issue was when the consist was run on my outside lower loop (O 72 with a section of straight between each 90 degrees). The track work needed to have at least one car length between curved sections of track because of the tilting mechanism. Also the bottom of the spacing portion of the coupling mechanism on each car needed some lube to permit it to freely negotiate O 72 curves.
All true, at least in my not entirely happy experience with this set. I also had a sense of deja vu reading this post - we have been here before three years ago, as witness this thread, which I think is required reading for anyone contemplating buying one of these sets or setting it up for the first time:
https://ogrforum.ogaugerr.com/t...-do-you-think?page=3
The coupling mechanism probably looked fine on the drawing board but it is very complicated with parts of the bodywork/skirting of each car moving out to allow for coupler travel on O-72 curves. The reference by rboateroo to lubricants that turn solid reminded me that I had an issue with the coupler spacing mechanism, which requires lubrication to prevent it wearing a notch in the plastic used for this part. The result of running the set on a large oval with O-72 curves where the train only ever turned to its left was this notch worn in the part preventing the coupler from aligning correctly:
