In the U.S., the name brand camera company wanted me to send my zoom lens to their facility in California to clean mildew from the elements. Their charge would be $550, a little less than half the cost of a new lens. That lens 
A third lens they did not want to clean as it was old enough they could no longer get parts for it if needed for reassembly. I had nothing to lose by attempting the work myself. On You Tube, people show how to take a similar lens apart but they never show how to reassemble it. I took it apart, and fortunately, took some still pictures along the way and used various colored Magic Markers to help with orientation of parts upon reassembly. I was able to get to all the elements deep inside and clean away the mildew. As a first timer, it took hours but I was able to get everything reassembled. Left over was only one plastic washer and surprisingly there were no spare screws laying on the table. Everything looked great……but mounted on the camera, nothing worked automatically. Into the trash it went. I was not going to spend more hours on the lens since I just bought a good used one for $75. But now I know that it is not that terribly difficult for an experienced repair man to clean deep inside a camera lens, and certainly, no where in the world should the charge be $550!
