Thermal Sensor
It cannot be repaired, just replaced, though on occasion you might have some success trying to clean it with a shot of spray carb cleaner (thru the "chimney" visible on the inside of the air cleaner body once you've removed the lid). Usually not.
They've been discontinued for a couple years; if you're not successful in locating one locally send me a PM; I have some new ones on the shelf. Before condemning the sensor, check that the system is hooked up correctly (vacuum hose from the manifold vacuum port on the carburetor to one of the sensor nipples on the underside of the air cleaner body, second vacuum hose from the other sensor nipple to the actuator pod atop the air cleaner snorkel) and make sure the hoses and actuator pod are good and not leaking air.