RedFish- The pin is out. So I have to tap the coupling to drive it further on the shaft where the cutaway lines up with the hole for the roll pin? What do you mean by the edge of the hole is a place to tap?
If you distort the cap on that coupling at all it will pop off and never stay in place again. You can use a drift and hammer tap lightly in the edge of that hole and not hurt anything. Sometimes I can just wiggle and shake on the coupling and it will move on down. a little WD-40 could help too.
