Had one of my ST SD40T-2's suddenly start derailing on a certain curve and, when I went to investigate the cause, I discovered that the lead truck was snagging something when I would swivel it by hand. Further investigation revealed that there was a somewhat tall solder blob where one of the truck wires attached to the truck contact strip and this blob would snag on the plastic underframe detail as the truck swiveled. I was able to carefully file this blob down enough to where it seems to no longer cause interference. I did this on another unit that also appeared to have somewhat snaggy trucks. Just passing this along in case someone else has a unit with mysterious derailment issues.
