Valve body on this old one is supposed to have a tang at 90 degrees to the right of the exhaust port hole that goes directly up to the exhaust chamber. (My terminology may not be correct). In reassembling I noticed the factory tang that aligns with a notch inside the barrel was virtually gone so I had no way of making sure it was aligned properly when assembled. I drilled a tiny hole where the tang was originally making sure I didn't go too deep and into the exhaust valve hole. I drove a wire nail into the hole, and cut it off. Still wasn't tight so I soldered it and cleaned it up. Reset the compression piston head space to maybe a 1/64" Put all pumping and body back together and with four pumps I got a loud crack. Still working on the wood and that's another story. This is my first rebuild on an old Sheridan. Still have a lot to learn.