there is a specifit kit at Oreilly's for a Hitachi 2Barrel that includes all these parts, it was around $35 or so, includes all the gaskets, pump, needle, i think the float was separate but was like $6, i have the old box, which is in the attic which i actually need to go for this afternoon for a wire brake safety low switch on the brat, so if you need an exact part number for the kit, im pretty sure i can get that for you.
but let's rewind alittle, when i removed my old needle, there was a bunch of like "carbon" build up inside of it, and that might be preventing it from closing completely and start leaking out, clean it the same way one does with the windshield wiper sprayers, i think toilet bowl cleaner right? in a zipploc bag.