The procedure to effect the removal of councilmen in addition to other methods provided by law shall be as follows: A petition signed by voters entitled to vote for a successor to the incumbent sought to be removed, equal in number to at least twenty per cent of the number of persons who voted in such municipality at the last preceding general election, demanding the removal of and the election of a successor to the councilman named in the petition, shall be filed with the municipal clerk. The petition shall contain a general statement of the grounds upon which the removal is sought. The signatures to the petition need not all be appended to one paper but each signer shall add to his signature his place of residence giving the street and number, if there be such. One of the signers to each such paper shall take an oath before an officer competent to administer oaths that the statement therein made is true as he believes and that each signature to the paper appended is the genuine signature of the person whose name it purports to be. Within ten days from the date of filing the petition the municipal clerk shall complete the examination and ascertain whether or not such petition is signed by the requisite number of qualified electors, and shall attach to the petition his certificate showing the result of his examination. If by that certificate the petition is shown to be insufficient it may be amended within ten days from the date of said certificate. The municipal clerk shall, within five days after such amendment, make a similar examination and determination of the amended petition, and if the certificate shall show the same to be insufficient, it shall be returned to the person filing it without prejudice to the filing of a new petition to the same effect.