I have 14 HP Briggs Vanguard Model series 261700, (manufactured 1990) that the carb keeps flooding when the mower sits unused for a few hours. Once the engine starts the engine runs fine. I replaced the needle valve and also cleaned the needle seat with carb cleaner and a cotton swab, the brass needle seat is not removable and seems clean. I checked the float for any leaks, but it did not find any. When the float is pushed up the needle valve seems to be sealing, as I cannot blow air through the carb fuel pipe with my mouth. Any suggestions on what else could cause this would be appreciated. Thanks.