I have not had the control valve apart to see what is inside. My parts manual shows a pin with a shoulder and head on the top (goes into the sliding valve) and a snap ring on the bottom. It looks like the pin also holds the “locating lump” detent casting to the shaft that the exterior lever bolts onto.
It would appear that you have to remove the back of the valve assy to put the pin into the sliding valve which is under spring tension.
I can scan the page I am looking at and post it if you would like.