I think those are kept in the hen's teeth drawer of the parts bin. Never had to find one.
I did not look closely at the posted image, but some carb<>governor links use a thin long spring to keep tension on both ends. If that spring is missing or broken, slop on either pivot point can get the governor to start hunting as it falls behind the rpm response of the engine. One other thing to consider if you have a hunting condition is the freedom of the linkage to move. The linkage should not bind in any position, full or closed throttle. The throttle spring should go to WOT if the manual control is advanced to full throttle position. I am not directing this at you, the OP, but as a general missive.
tom