I sent my battery free medium format cameras for a CLA service. Wondering about newer cameras, does a CLA service exist and to what level? If you take a modern Nikon F5 or a Canon EOS 1v / 3, or a Canon EOS 5D / Nikon D810 camera film or digital, full of electronics, apart from adjusting the mirror, the aperture lever and 1 or 2 foam seals what else is there? Is there a lot less to do than a battery free camera? How important are they on these cameras? Many thanks.