Yeah, that' s not supposed to come off! It' s kind of common amongst those old MKI' s though, they' ve been used a lot, they should be too, they' re great guns, that just tends to wear out before most other parts in there (Ol' Willie, rest his soul, built a great gun). You could probably just go down to a local gunsmith and get the part replaced, I' m fairly certain that it' s interchangeable with the MKII' s recoil spring piece.