RE: Brison 3.2 Carb Help!! (Where is Ralph when you need him!)
Ditto both RCpilot and Roy.
If possible, use a pressure tester (pop-off tester) or pressurize the fuel line. If the main metering needle seats well, there will be no fuel leaks with the fuel supply line under pressure. If it does leak with the regulating membrane removed, the fuel needle and/or stuck fulcrum lever and/or fulcrum lever spring can be the only culprits.
With a micrometer depth hauge check fulcrum lever height. Too high a lever setting will leak fuel all the time. In most carbs, it should be equal to the surrounding casting, or the carb body with membrane gasket in place.