2V help needed

The carburator on my 273 is a Ball & Ball.
It has been rebuilt by my mechanic but has
not performed. Now it is flowing fuel out the top
like the float wont hold and loading up & flooding
out at idle. Can this be tuned or do I need to replace
it with another 2v carb of another brand, and if so what
should I look for.
Thanks, Rat