Apologies...  just realized you were talking about centering shift linkage.

Manuals are in Tech Library here...  just not sure if TY would be same as DT.  (TY engine was a bit of an odd duck in some respects and I don't have a manual)

Thank you MarkT. I see how to adjust the Shift Linkage left and right about the Dowel Pins. I just don’t see how mine is hooking well enough the pins to actually rotate the drum in either direction. Seems it’s not reaching up enough. That’s why I wonder if it’s worn out. 

Red background is the new one I saw on line.

I've never seen one wear out. But could be.

I have seen a lot of people struggle with "bench shifting". Get someone to spin the clutch input shaft continuously while you try to shift. Also make sure you have all the "detents" in place. (spring and plunger that engages cam on shift drum for sure)

They just don't shift well on the bench in my experience.

Thank you MarkT. Ok, excellent advice. I have my head around the gearbox. Now turning my attention to the shifting mechanisms. 

#9 the TY. If you're trying to go through the gears without the plunger & spring it'll be up the creek. Plunger keeps it fully in gear n& then the claw arm will hook the next pin. Plunger & spring would make it hard to change gear on the bench unless held still & gear lever to operate the drum. If i'm on the right page, but hope ya sorted.