What Locks the Upper Column Collar?

66 Barracuda, four speed, no power steering. I rebuilt the column, putting it together now. Testing the turn signals switch, but the collar spins a little in both directions when I flip the switch. I've pressed and tried to get the collar to interlock with the column with no luck. I haven't put the steering wheel on yet. Does the wheel somehow mash everything down to lock the collar down?