Looking at your pic's I can't see what the problem is... the O ring on the needle looks intact to me? was the needle leaking? if so the O ring on the needle is what seals up gap between the needle and vavle body... you also have a gasket between the valve body and carb. If you tried to fit the O ring into the valve body that's your problem... it don't go there. Slip/cut off the O ring on the needle and replace it with a new one by slipping it over the needle and letting it seat in the grove. If you want a temp fix take a piece of large fuel tubbing and slip it over the needle and valve body so that both the needle and valve body are sealed together... it works

John