That is a common problem. You might try getting a new o-ring for it. The old carbs on the Tecumseh engines are rough. I put a brand new carb on my last Tecumseh in a Swamp Fox. Sure made it run good. New cost is about $125.
I'll have to look around and see if I still have the box to that carb. It was somewhat difficult to find the model number for it. I ordered from a lawn and garden place in MN. I'll post back tomorrow with what I find.