Each member of Council shall be an elector of the City and not otherwise employed by the City. Any member who ceases to possess these qualifications, or who is absent for three successive regular meetings without authorization by Council, shall forfeit office. Council shall by rule determine and list conditions and circumstances which constitute good cause for absence. If a vacancy occurs during the final two years and six months of a term, Council may fill the vacancy by appointment for the remainder of the term. Otherwise, Council may fill the vacancy on a temporary basis by appointment, effective until the first day in January following the next regular municipal election that occurs after the vacancy. The unexpired term shall then be filled by the successful candidate for such term in that regular municipal election. Any vacancy remaining for more than 60 days shall be appointed by the Mayor.