A drop of Conducta-Lube about to be placed on the spring-brass contact arm (the long, thin gold-colored item.) This arm contacts a brass vertical arm under the center wheel; the arm can barely be seen: the tube is pointing to it.

Both should be cleaned with rubbing alcohol first. (Cleaning is more important than lubing here!)

Micro-trains Coupler height gauge (on track), trip pin gauge (rectangle below left) and NMRA Standards gauge (below right), shown with an Atlas N-scale RS-3.

http://www.micro-trains.com/