Automatic Column Shifter problem - 75 Bronco

[Waldo]

I have a stock 75 Bronco with automatic transmission and original column shifter. Today the shifter would only move between Park, Reverse and Neutral. It felt like it was mechanically blocked from moving into Drive or lower.
Disconnected the linkage at the transmission and can move the transmission into all the gears (P, R, N, D, 2, 1). The problem obviously is with the shifter. Even when disconnected from the transmission, the shifter will still only move between P, R, and N.
Reviewing various posts online I suspect there may be a shifter collar issue. However I am wondering if there is a lock out or something similar that I have overlooked.
What say the crowd? Do I need a new shifter collar? Or is there an easier fix?
Thanks

 

[RT]

There is a dedent ? type plate in the column . mine broke a few years ago and made shifting feel funny

I replaced it , now it'll stay in park . Luckly I didn't find out the hard way it would fall into reverse

 

[Viperwolf1]

Either the collar or that detent plate is broke. You need to take it apart to see what it is.

 

[Waldo]

Thanks for the inputs. Will commence dismantle this weekend.