Whatever track you use, be sure you try and stay with the same "code." Several articles I have read recommend "beginners go with code 80 as it is a little heavier duty and more forgiving", not that I am saying you are a beginner. I used Atlas Code 55 on my first layout and it seemed to bow in when I was cutting the rails. Am switching to Code 80 on my new layout.

Have the above loco. Wobbles when it runs. Noticed a small rubber band on the forward most left side drive wheel, but none on the forward most right side drive wheel. Am I missing the rubberband on the right side, or should I take the rubber band off the left side.?