Whenever a member shall be six months in arrears in the payments of his dues upon unpledged shares, the secretary shall give him notice thereof in writing and a statement of his arrearages, by mailing the same to him at the last post-office address given by him to the association. If he shall not pay the same at the next or second stated monthly meeting thereafter, the board of directors, at its option, may declare his shares suspended and, at the time of such suspension, the withdrawal value thereof shall be determined and stated, and the defaulting member shall be entitled to withdraw the same without dividend within one year, upon such notice as shall be required of a withdrawing shareholder, or such shares may be transferred to a prepaid share account or a savings share account.