Nonconforming signs may be maintained, repaired and repainted without a permit or fee; however, the sign, other than change of copy, may not be modified (unless the modification brings the sign into compliance with this code), expanded, relocated, or structurally altered. Maintenance excludes major structure repairs designed to extend the useful life of the nonconforming sign. If the nonconforming sign is damaged by wind, fire, neglect, or by any other cause, and such damage exceeds 60 percent of its replacement value, the nonconforming sign will be removed. Upon change of use of a business or premises, a nonconforming sign shall be brought into compliance with this code within 180 days. [Ord. 3790 § 8, 2006; Code 1970 § 17.15.020.]