I have a kaw fc420v that will start to leak fuel out of the carb vent tube. I took the float bowl off and made sure the float was moving. Put it back together- ran it for 20 min. no laeks. Mower sat for 12 hours and started to leak again. I belive it is the needle and seat not closing making the float bowl overfill and run out the vent. But I do not want to order parts (3-4 days) to find that it did not fix it. Anyone ever had this problem?