the bowl gaskets are probably old and dry.
get a pair of blue gaskets for your metering blocks and bowls. it'll be easy to replace them. just remove the bowl bolts, put a rag under hte bowl to keep gas from going everywhere. tap the bowl with the head of a screwdriver or rubber mallet to break the seal and it should fall off. clean the surfaces, put in the new gaskets and put the bolts back in the bowls and do NOT overtighten them, they strip easily.



if they're old you might as well just get a rebuild kit with new needle cork seals, bowl gaskets, accelerator pump gasket, etc.