OM1n's do not have the foam rot problem
I do not believe this is correct.

John Hermanson posted on apug (forum search)

Yes, every OM-1, 1N, 2, 2N I see now for overhaul need new foam at the hinge, slot and mirror areas. John, www.zuiko.com
If John says all OMs need mirror foam, they all need mirror foam!!