Thanks everyone for the replies...
Thanks Scotty! The manual for my H23.5 doesn't have that diagram. I remember it was slightly odd shaped, not that it's too critical.
Years ago I bought a 12x24 piece of UHMW to fashion shims for the tiller, where it's sandwiched between the top of the rudder plates. I'm pretty sure I kept the leftovers, but now I'm 90 minutes away from the boat for a few days so I'll to wait.
I guess what remains is how to figure out how to get the pin out. Maybe grab it between the sheaves with needle-nose pliers and try to push it?