Some people use tiny dabs of superglue. Some use liquid gasket or gasket sealer, but I don't recommend that because those products swell a lot in gasoline and if a piece breaks off you'll be pulling the carbs to clean them out again. Some people use grease. I like to use scotch tape. Tape the gaskets down, partially tighten the bowl down, pull the tape out and tighten the rest of the way.