Sec. 10.5. A person who is serving as a full-time magistrate on July 1, 2010, may elect to become a member of the judges' 1985 benefit system under this chapter. An election under this section:
(1) must be made in writing;
(2) must be filed with the board, on a form prescribed by the board, before October 1, 2010; and
(3) is irrevocable.