Pre-2000 Strowger selector demonstrator

I have built a demonstrator to show the operation of an early two-motion selector that was used in Strowger telephone exchanges all over the world. In the USA these exchanges are called central offices and the selectors are known as step-by-step or SxS. My selector did not come with the associated relays to control its operation. I have added a few components to bring the selector to life.