I need to clarify what I wrote about foam rot. I meant to say that the prism damage that occurs on OM1 and OM1 MD cameras will not happen to the n variants because they are not foamed there. All of the foams ( not the silk cord) used on camera seals and mirror bumpers (and elsewhere) in the late `70s and in the `80s has rotted. Classic audio equipment buffs have found that the same urethane formulas were used for many loudspeaker surrounds and they are all goo now.