I have a spare 127mm Mamiya Sekor C lens for my RB67 that needs work. The painted coating on the outside of the rear element is flaking off inside the barrel and as this is a spare lens, and even in good shape they sell for peanuts, I'm thinking its a good candidate for my first lens dis assembly/repair procedure. I need to order or make some lens wrenches I guess but what about the paint? What can I use? Those of you who may have opened the back side of one of these lenses is there anything to be aware of? I wont need to tinker with the shutter, just remove, clean, and repaint the rear element.