(a) At least once in each four years, the board shall conduct a check-up of each registered elector in the election district by any method deemed necessary.
(b) For the purpose of facilitating any such check-up, the board may, when necessary, appoint special inspectors of registration, in number not exceeding double the number of polling districts which the board shall determine to canvass.
(c) Special inspectors shall have and may exercise the powers conferred by this chapter upon inspectors of registration. They shall be qualified electors of the election district, and shall be appointed without reference to residence in polling districts or to their political affiliations or beliefs.
(d) The board shall instruct each special inspector in his duties.