How can I fix my Briggs & Stratton rototiller carbuerator?

I have a Troy rototiller with a B & S 6 horsepower overhead valve engine that is not drawing fuel from the tank to the carb. It will start as long as I am choking it but will not run when I quit choking. I have cleaned out the old gas from carb and tank, cleaned needle valve. The small brass screw on bottom of carb has two side holes and orphus in middle that was plubbed and I cleaned them out. Sprayed carb cleaner in all orphus holes and blew out with air. What do you suggest?