I just recieved a remington 540xr target rifle. the gun has failed to eject spent shells a couple times. I believe that the person who gave it to me has not cleaned it in the last 10 years. although the gun is still in excellent shape. Does anyone here know how to field strip it so that i can clean it? Also, reminigton no longer has the manuals avbailable. could someone direct me possibly to an online source so that i can view it?