Yes, Bruce, we were having troubles in Nelson Yard with some rolling stock. Part of the problem was aged LGB 1600 switches that had seen better days. Second was some wheels were out of gauge, and all the cars that gave trouble seemed to be on the light side, weightwise.
So you see, it usually is several things that cause derailments, and you shouldn’t always blame one without checking everything.
The unfortunate occurence is that if a car is light, it attracts attention, and the light weight is blamed first off for the problem.
We just decided to be more particular in our standards for good rolling stock performance, and are checking all possible causes for derailments.
In the case of Nelson Yard; we already knew we had a growing problem with rail dynamics, and next Spring will see a rebuild of the yard.
So, as I’ve been saying; derailments can be caused by any one or a combination of about 5 different things, and to avoid checking them all will never solve derailment problems.
Derailments lead to frustration, leading to lack of fun, in Model Railroading.