Signs in existence when these sign regulations became effective may continue in existence subject to the following:
1. The lawful use of a sign existing on the effective date of these regulations, although such sign does not conform to the provisions hereof, may continue; but if such nonconforming use is discontinued for a period of one year, any future use of such sign shall be in conformity with the provisions of this chapter.
2. A sign shall not be altered structurally or moved unless it be made to comply with the provisions of this chapter, except that the changing of the movable parts of an existing sign that is designed for such changes, or the repainting or reposting of display matter shall not be deemed a structural alteration.
3. No sign which has been damaged or destroyed by fire, flood, explosion, wind, earthquake, war, riot, or other calamity or act of God to the extent that 50 percent or more of the sign is destroyed, shall be restored except in conformity with the regulations of this chapter. Any sign which had been damaged to an extent less than 50 percent, may be restored to its condition which existed as a nonconforming use prior to its damage. Restoration or reconstruction shall commence within six months from the time of loss; if not, then the sign must be in conformity with the regulations of this chapter.