The licensing agency, after notice and opportunity for hearing to the applicant or licensee, is authorized to deny, suspend, or revoke a license in any case in which it finds that there has been a substantial failure to comply with the requirements established under this chapter. Such notice shall be served by registered mail or by personal service setting forth the reasons for the proposed action and fixing a date not less than 60 days from the date of such mailing or service, at which the applicant or licensee shall be given opportunity for a hearing. After such hearing, or upon default of the applicant or licensee, the licensing agency shall file its findings of fact and conclusions of law. A copy of such findings and decision shall be sent by registered mail or served personally upon the applicant or licensee. The procedure governing hearings authorized by this section shall be in accordance with the usual and customary rules provided for such hearings.