Thermoquad base gasket leak

You got more than an air leak. You got raw fuel leaking, and Thermoquads are known to develop a leak in the mainwells. My advice is to separate the black part out with the carb FLAT on the table, then look into the cavities under where the mainwells are; I bet you'll find gas in there, and it ain't supposed to be there. If so, your bowl is gonna need repair.