Could be float, needle, warpage, as noted above. Advice: Rebuild per internet videos and check flatness of mating surfaces. Gaskets usually last a long time. Have you done anything to carb? Did this just happen out of nowhere? When is last time it was opened up? Dirt particles can get in and around needle and seat or they are degraded by time. A good cleaning and rebuild usually fixes all. New filters a must. Does it run good? It should have trouble idling or running under load to confirm dirt in system. Adding more gaskets or tightening would be the wrong procedure. If you find warpage you can fix several ways. Others here can state what works best and is the safest. As I said above there are videos and they do address warpage.

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