Stanley Bostitch F21PL Nailer "screw fell gun" Questions

...gun up side down, it fell up into the body of the gun. HELP!! sounds like the plunger has broken, four allen head screws on top of gun remove and pay attention to each part and how it comes out. not ...

...gun to fit new circuite assem. small spring and z shapedflat steel piece fell out from the nail exit jim Its called a lock-out, it goes close to the nose. On either side of the nose there are two ...