All I did was cap off the exhaust port with my thumb, finger to cover the fuel nipple, and blow into the carb. Then you listen for an airleak. If air is leaking around or through the carb, you'll hear it and / or feel it real quick. I had to remove the back plate and seal it off with the palm of my hand to verify that air was leaking between the cylinder sleeve and casing. Once the sleeve is removed, it was verified without a doubt.