In the case of advertising signs, as defined in § 300-10, the owner of such sign and, in the case of all other signs, the owner of the sign and the owner of the premises on which such sign is located, shall be jointly and severally liable to maintain such sign, including its sign face, source(s) of illumination and its electrical and structural elements, in a neat and orderly condition and good working order at all times, to repair all damage to such sign and constituent components in an expeditious manner and to prevent the development of any rust, corrosion, rotting or other deterioration in the physical appearance or safety of such sign.