There should be additional holes in the governor lever and the throttle lever on the carburetor. Throttle return spring goes over the governor link and then connects to the two unused holes. Design is to put slight tension on link and eliminate any backlash where the holes have enlarged.

this will help reduce hunting, but if idle circuit is too lean, rpm's will continue to hunt.

Great!!! thanks ggoyeneche. I found the extra holes and installed the spring but that didn't cure the hunting. How do I adjust the idle mixture? There are two screws on the top of the carb. One looks like the idle screw and the other one looks like a mixture adjustment. I tried adjusting both screws but nothing changed. I have now returned them to their original position. What should I try next? When I previously mentioned that I cleaned the carburetor, I didn't really clean it, I just removed the bowl and float and cleaned the little needle on the float and poked a needle into the hole. That procedure got it "running" (it didn't run at all before) but maybe I should actually clean it. Any additional help would be greatly appreciated.