Here is what PO did to the carb.
I totally disassembled except for the throttle plates and idle mixture needles and springs and soaked the body, air horn, secondary diaphragm cover, and accelerator pump cover overnight in a 5-gallon bucket of carb cleaner. rinsed with water and used a spray can of carb cleaner to blow out the venturi and jet passages. I reassembled with new accelerator pump diaphragm, secondary diaphragm, elastomer valve, air horn gasket, venturi gaskets and new fuel inlet needles, needle seats and gaskets. I made sure the primary venturi was stamped M and the secondary venturi was stamped B A. Installed secondary ball check, baffles, float springs primary booster venturi weight and accelerating pump check ball discharge. Also made sure the jets were 51 primary and 70 secondary. Checked to make sure all moving parts were operating freely. The new parts primarily came from the carb rebuild kits