got this from bli - it worked:
That model is thin and top heavy - it's going to always do that on a table with your finger on it so I am assuming that you are saying it does that while running on the rails as well?
Perhaps you could pull the trucks down and out of the chassis and adjust the tension on the copper pick up wipers to reduce the amount of side to side movement the model has?
Try and make them stiffer, bend them down towards the plates on the trucks more.