You can have the float bowl off the carb. Attach a line so there is a source of fuel to the carb. Now, with gas available to the carb., does raising the float, stop the flow of gas going through the needle and seat? Now, also remember, that the float is floating in gas in the float bowl and does not have allot of upward pressure that your fingers can give it. If in doubt, just replace the needle and seat. I have not priced them lately, but chances are they are still rather inexpensive and the ones in the carb. are probably worn. Sometimes even running a wire through a seat, can leave enough of a hardly visible scratch, to make them leak.