Thanks for the dialog, folks. Original post has not been edited. There is no need to hold the knob, as the spring-loaded cap holds the pivot ball down which keeps the shifter ball engaged in the shuttle below. But without the pin staying in place to index the pivot ball the shifter can be "stirred" all around even in gear. Those who thought it a roll pin in lieu of a solid pin hatched the idea that perhaps a roll pin might indeed suffice as a substitute and lock in place on its own. Will look into both that and making a keeper tab to hold the original solid pin in place. I have sourced a rebuilt shifter assembly now, so if my "experiments" don't result in a fix, I'll swap it all out in the Springtime, when it's a bit more comfortable to lay on the concrete floor in my garage! Cheers, and Merry Christmas!

It looks like I totally misread se7en's post. Maybe the guy edited his post. Are you holding the shift knob as you drive?

The pin he is talking about is on the shifter housing. One of the ones that holds the metal retaining cup on that also protrudes inside as the locating pin for the shifter.

Run a wire through loose pin as already suggested or........

Get one of these from our host - https://www.minimania.com/part/MSG13/Rod-Change-Gear-Selector-Coupling-Quick-Release

Job done!

Could you weld on an extra layer of metal on the pin and turn it down in a lathe to make it slightly larger than before to fit the larger hole? Or use some good epoxy to glue the pin in place?

Can you wire it in? As in put a piece of wire through the roll pin and then twist it together.

What I did was to find a small diameter SS screw and screwed it into one end of the roll pin. You don't need much, just enough tightness so it doesn't walk out on you again.

Rod change shifter as noted in the title. Can anybody offer help regarding the right side shifter retaining cap pin in the shifter housing that also indexes the shifter in said housing? The pin has "walked out" such that the shift lever has become free to roll around in the housing. It still shifts, but does not stay in the conventional "H" pattern. Very disconcerting. I fitted a new pin from my spares, but it is clear that the hole in the housing has enlarged and will no longer hold the pin in place. Was thinking that I'd tack weld a keeper tab on the outside of the slotted metal retaining cap to keep the pin from walking out again. Sound viable or does anybody have a proven solution short of fitting a new shifter housing? Thanks for whatever suggestions/help you can offer.