I have a Savage 10 chambered in 308 that I've had for about 20 years with over 2000 rounds fired. Recently I started having intermittent misfires and then about a month ago it stopped firing. So I took the bolt apart, something I've done in the past with my other Savage rifles to change the head. As I was removing the large rear screw I noticed there was more tension on it than usual. When I removed the contents a small piece of metal fell out. I noticed this small piece of metal went at the rear of the spring, so I took the firing pin completely apart looking for the remaining broken part. What caused this and can it be repaired.