I wouldn't jump to that conclusion just yet. Carb cleaner evaporates very quickly. With it being sprayed so close to the carb inlet I would imagine that a good amount of the solvent gasses are getting ingested through the air filter into the carb body displacing oxygen and killing the saw rich. The only way I can think of to know for sure would be to, somehow, attach a runner tube on the inlet side of the carb that is a foot or more long to insure the engine is only breathing standard air when you spray the base with solvent. I, actually, doubt you have an air leak there if the gaskets look good.