There are bushings on the shutter curtains that wear out on the early titanium shutters (the ones that don't have the one curtain with only partial honeycomb patterns on it), so any early FM2 or very early FM2n, plus early FE2's and FA's that will develop this issue. Especially if the shutters are fired a lot at 1/500 or 1/4000. You wind up with it firing at 1/8000 or 1/1000. From what I've read, the problem doesn't affect the shutters with the replaceable curtains (the shutter that has the partial honeycomb on one curtain, as well as the aluminun shutter used on late FM2n bodies). Replacement shutters can be had for FE2's and FA's without cannibalizing another of the same. I've seen a few FE2's and a couple FA's that had N8008 shutters installed, which are what the late aluminum shutter on the FM2n is based on. And probably what the FM3a shutter is also based on, just with a different mechanism to control the shutter speeds.