The little gasket on the nut looks mashed. Needs replaced. Don't think there is one on the inside.
Is your needle seat sealing?
You should be able to pick that up at your local small enginerepair shop.
You can get a package with a new needle, seat gasket,bowl gasket,and gasket for the bottom of the bowl all in one kit. About 8-12 bucks.
While you have it all apart,might as well clean everything real good with carb cleaner. Make sure you clean all of the jets holes as well. Should be 2 tiny little holes on the jet(that thing that unscrews from the bottom of the bowl). Good luck. Any more questions,ask away.