Many times the carbs will show wear in the little bracket that holds the air cleaner rod. Here is a pic
That is the issue with my latest B. The entire bracket that holds said rod has broken off of the airhorn, likely from previous owner(s) overtightening the air cleaner hold down nut. I am either going to have a Rochester B graveyard soon to continually mess with these finicky suckers, or replace it all and try and get a different carb on it.