The term of office of each member of the Board shall be six years, except that the terms of the two members, other than the Chairman, first appointed under subsection (a) shall expire, one on the expiration of two years after the date of appointment, and one on the expiration of four years after the date of appointment. Members of the Board shall not be appointed to succeed themselves, except that the members first appointed under subsection (a) for a term of less than six years may be reappointed for a full six-year term and members appointed to fill unexpired terms of three years or less may be reappointed for a full six-year term. Any vacancy shall be filled for the unexpired term on like appointment. Any member of the Board shall continue to serve as such after the expiration of the member’s term until a successor has been appointed and qualified.