I have two green CN coaches made by Athearn. I bought these new last year. Of all my rolling stock, these are the most prone to derail. They are very sensitive to any track imperfections -- if anything is likely to derail at a problem area, it's these coaches! I recently adjusted my track and my rolling stock runs fine on my layout except for these two coaches, which is often the case. One of these CN coaches -- a shorter baggage car -- is worse than the other (which is a passenger car). The gauge of their wheels appears to be accurate. I also recently added some weights to the baggage car. But the baggage car is still giving me some problems at one area, while the passenger car runs OK. I was wondering if anyone else has had these problems, either with Athearn products or similar CN coaches (i.e. similar green 1950s CN coaches, but made by another company)? I suspect that these coaches are quirky because they're relatively short and each have two 6-wheel trucks. Are the problems due to the manufacturer or are these simply difficult coaches to model and run on a model railway? Does anyone have any other suggestions? Thanks in advance! Otherwise, these are fine-looking coaches and look great hauled behind my CN C-liner.