I have an FM that does the same thing. Just get it overhauled or if spending money on a camera that would get $50 working on eBay puts you off, just use it at other shutter speeds (Mine only exposes 1/3 of the frame at 1/1000, so I use it at 1/500 or slower). Run some slower film and you'll be fine. A third option is to try and fix it yourself (best for cheap cameras of eBay, not for family heirlooms).