Any person retired for disability under this chapter may be summoned before the board at any time thereafter, and shall submit themselves thereto for examination as to their fitness for duty. If the board shall find such person fit for duty, it shall order them to return to duty and shall order that their pension cease. Provided, however, that the provisions of this section shall not apply in the case of a person who has elected to receive the service retirement benefit as provided in Section 4.28.090 hereof. (Ord. 3558-NS § 12, 1957)