1974 IMP 18'6 Ford302, Holley four barrel. Almost done with the restore on the boat. When running it (on muffs) the engine sound fine, good idle speed, etc. However, when I turn off the motor, some fuel leaks out of the carb at the thottle pivot shaft. It leaks some on both sides of the carb, but more so on the port side. The guy before me said he had rebuilt it (I have his receipts for the kit),but he may have only test run it a couple of times. I don't know if there is a seal or bushing on that shaft the should ave been replaced or ?????? Any ideas or suggestions?