I have a Browning Auto-5 and the firing pin is sticking every second or third shot without firing the shell. Is there a way to get to the firing pin to clean and oil it without disassembling the entire gun? Is this the problem or would it be a weak spring? I just received this gun from a relative, so it is probably used and has yet to be cleaned even though it looks to be in great condition. The gun is hard to disassemble, I have yet to find a screwdriver thin enough and strong enough to not break when attempting to disassemble the frame. Thank You for any help!