hey devans I sent you a PM also- if you load up the macine with a needle and tube and rubberband. then roll the bearing until its at the top center. then move you tube until the needle is just level with the tip of the tube now lock you vice. then roll you bearing around until it is bottom center and use a small metel ruler that measure in mm and measure from the tip of the tube of how much needle is hanging out and that is your stroke.
i remember that dan kubin and a video up on his site one time that you can watch