On any nonconforming structure, or portion of a structure containing a nonconforming use, work may be done on ordinary repairs, or on repairs or replacement of nonbearing walls, fixtures, wiring or plumbing, provided that the cubic content existing when it became nonconforming shall not be increased. Nothing in this section shall be deemed to prevent strengthening or restoring to a safe condition of any building or part thereof which is unsafe. Not replaceable if sixty six percent (66%) of the structure is destroyed. (Ord. 15, 7-11-1977)