[Johnson] Roto-Matic Rotor

[radio]

I have the indicator portion of the Johnson Roto-Matic Rotor, maroon wrinkle finish.  It has three holes across the bottom front of the indicator unit.  The far left and right have switches, which I would guess are for CW and CCW rotation.  The middle hole is empty, can anyone tell me what that is supposed to be used for? On-Off?  What kind of switch?  As I recall, there may have been a overlay panel across the bottom.  Can anyone shed some light on this?
Thanks,
Paul, W9PJ