Well, the needle will have a small v shaped neoprene on it, and the seat will hopefully be a circle that the needle will go into. Take the secondary bowl off, raise the float up and blow into the fuel inlet. It should not allow air through with the needle seated. Doesn't take a very big piece of dirt to make one of these little boogers stick!!!! Check it close. At my age and deteriorated vision a magnifying glass is essential!!!!!!