I have a 66 Cubcadet 122 that will start and run on a low idle but won't idle up when i push the throttle lever up. I have looked at all the linkage to see if it is moving correctly and it is moving correctly. I have also looked inside the carb to see if the butterfly is moving and it is. I have no idea what to try next or what is even wrong with it if anyone has a suggestion or knows what i can do to fix it please let me know thanks.