When I was cleaning the bolt on my l579 I noticed the firing pin assembly was loose. When I started to tighten the flathead notch, the bolt assembly popped out of the bolt and I don't know how to put it back together. There is rust and corrosion on the firing pin and it's assembly, would that have caused this ? I recently purchased the rifle from a lady who's husband had left the rifle in a closet for the last 30 years. What should I do ?