For what it's worth I've been bothering him through his shop phone, but he seems up to his eyes some days, just got a shorter stroke one piece in the post (next day post here in UK, sorry!!) to try for shading, it seems to run a bit faster per volt, maybe the motor, or would a slightly shorter stroke do that anyway, the cam still has to to do the complete revolution, or is there a little less inertia to work against the torque of the motor, or am I talking b****** and it's just my imagination.