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It's almost never the air switch actuator on the tub. Much more common is the tubing falling off the switch or the actuator. Sometimes the tubing can get kinked. You rule out the switch at the pump by first activating it at the pump then (if that doesn't work) jump out the switch to be sure the motor runs. The actuator at the tub is held in place by a lock nut on the underside of the tub.