My guess is for longer duration for that switch stack. I'd have to see what switches are on that stack and where they correlate on the schematic. I have a Bally EM relay / motor board out for service now. I'll look and see if there is one like that on my game (not Night Rider).

All of my blades are the same.

When I service a score motor and switch stack, I print the schematic and highlight each score motor point on the schematic. Then I go page by page looking at the schematic and associated contact. It helps define normally open or normally closed and which point may be just out of adjustment.

Flashlight and small plastic tool is necessary.