Heater Control Panel Removal-73 Dart Sport

The one bulb socket is in right side of the controller head. Pull the glove box liner.
Thank you...found the wire with the plug and the light attached and it works. However...it has a round push-in type socket and I cannot find where it would push into to save my life. Seems I've been all over the back and sides of the control with my hand and still cannot find a round hole anywhere. There's no radio in it so I can see in but still don't see anywhere it would go.
Any other hints??