I would replace the gaskets anyway. Since you took it apart, are you sure the carb gasket was installed correctly (crankcase vent hole lined up), diaphram gasket installed the right direction, flapper gaskets not too loose or floppy, screen filter not clogged. Sometimes opening up the carb sides and flushing it with some fuel, then putting the sides back on is needed to sort of prime the pump. I've never had to do that but others on here said it worked for them. I usually start with removing the plug and spinning the prop with a starter to see if I get any or how much fuel movement. I've been bit more times than I like to admit to having the carb gasket missaligned just enough to restrict the pump action from the crackcase.
Edwin