On my Dads '56 Merc we took the float out, found the source of the leak, scuffed it a little with some sand paper so solder would stick, and soldered it up. The pipes in your house's are brass, the same solder and flux work great. just make ABSOULTELY sure the float is rinsed clean as a whistle before applying flames to it, trapped fuel fumes in a little brass container tend to go bang!
