Warm the float up with a hair dryer while rotating it and you will see where it is leaking.
(A pair of jewelers glasses are helpful, or a magnifying glass)
Then take a pin and enlarge the hole so you can drain it while applying heat from the hair dryer.
Ya don't wanna use an open flame as it is after all, flammable fuel inside.
now when it cools solder up the pin hole with a soldering gun or iron and all is well.
BTDT multiple times over my many years.
Never had one I couldn't fix
