I need to see another of this exact radio as I understand how it works but need to know what goes in the little knotch in the middle of those 2 metal shafts.

What is the make and model of you're radio? Usually a notch(or fork) provides a pivot for a pawl(or finger) to rock in when the shaft is turned. This in turn actuates a switch or other control. Maybe the finger has broken off(?),it may be tiny,look around the chassis or cabinet floor for it.