The clip snaps around the needle then the little flat part of the clip goes around the the tab on the float support. It just rest there doesnt seem secure but that is how it goes. When the float goes down the clip pulls the needle down with it. When the float raises the tap on the float support pushes on the needle to close off the fuel suplly. As far as your fuel leak there is an O-ring to seal the bowl, if you dont see it than it is stuck up under the bowl housing on carb body. If you cant figure it out email me at email@example.com
and I'll dig up my parts list and send you a picture.