I was replacing all of the shift linkage bushings when I ran across an interesting problem. All of the bushings appeared fine visually but they had certainly been there a while so I decided to replace them.
In particular the coupler bushings seemed to be causing the coupler to bind. Even manipulating the coupler manually was difficult and it would stick in various rotations. The best way to convey this is this video:
Stiff Coupler - YouTube
Removing the pin offered a bit of resistance and when it was out I noticed two identical scars/scratches on the pin.
I test fit the pin back into the central metal portion of the coupler (with the splines) and it binds about this point:
In the process though I did find a nice gentle way to remove the coupler bushings. Using a bolt and nut it was pretty easy to draw the bushings out without prying etc. near the somewhat delicate cast coupler.
It seems that our host does not sell the coupler pins alone. Any suggestions for a replacement or repair appreciated. Perhaps I'll just need a whole new coupler...