Rear element removed. This element underwent the same treatment as the front. Soaked in ammonia peroxide solution and cleaned. Some of the black paint flaked off the edge of the cemented elements. I used some epoxy model paint to re coat the edged and let dry overnight. At the minimum, use a black sharpie to re paint the edges. The black paint is there to prevent lens flares and weird artifacts. You will most likely notice what appears to be dust on the lens...On close inspection under a magnifying glass you will see it isn't dust but air bubbles in the glass. Old glass tends to have them and they will not affect the performance of the lens.