If the capital of a bank becomes impaired, whether the department has taken possession of the bank or not, and if stockholders representing eighty-five percent or more of the common capital stock of the bank, with a view of restoring the impaired capital, shall, with the approval of the department, authorize the board of directors of the bank to levy and collect assessments on the common capital stock in such amount as the board of directors may determine necessary for such purpose, the board of directors shall levy the assessments so authorized and shall notify all common stockholders of record of the assessments by either registered or certified mail. If any common stockholder fails to pay his or her assessment within three weeks from the date of mailing such notice, the pro rata amount of such assessment shall be a lien upon his or her common capital stock and the board of directors shall immediately sell such shares of common capital stock at public or private sale without further notice and apply the proceeds of the sale to the payment of such assessment. Any balance shall be paid to the delinquent shareholder. Nothing in this section shall be construed to authorize the levy and collections of assessments on the preferred capital stock of the bank.