Simon Rodia was a great artist and dreamer who built the wonderfully decorated Watts Towers all by himself. Unfortunately, they are made of relatively flexible steel and rigid and brittle concrete, mortar and tile. The towers will move and deflect as they respond to the weather and earthquake forces, and in so doing, the rigid elements of the cladding will break, unable to physically flex with the steel's movements.
Engineers have always struggled with the balance of strength and stiffness. Rodia, not concerned with this dilemma, used the most immediate materials at hand. Some structures, unfortunately, are not meant to survive forever.
The workers who are struggling to maintain the tile and glass decoration will have to anchor the decorative elements with a relatively flexible substrate that will allow the exposed steel structure to move and respond to the natural elements. I wish them well and hope they can solve the problems.