I've always been a Nikon man(FG,n6oo6,n80-with plenty of lenses)but I recently dropped my guard and bought an Elan iie and a 630.These cameras have to have the shutter cleaned of black goo periodically just to get 'em to work.I've been told that its the shutter bumper disintegrating,in both cameras!!How common a problem is this for canon fans? Does it happen to Nikons?I've got several other slr's-Pentax and Olympus mainly but I've never seen this before.What gives?