Great info here. Thanks, guys. I disassembled it this morning and it looks pretty good except that the contra piston is stuck in it's bore. I'll probably soak it in oil or kerosene and then heat it up to see if it'll break free. Question: Is the compression screw supposed to be attached to the contra piston? Mine is not. If not, then what keeps the contra piston from slapping up and down beating the other piston to death when running. As it is currently, the piston is hitting the contra piston just before top dead center.