Finally, a little more Puffer progress, as I didn't want to run a wire linkage across the rear deck for the rudder, I have opted for sprockets and chain which I think looks for in keeping with the original method of operating. Plus of course, I have already opted also for chain drive from the prop shaft to the steam engine as a method for getting the prop shaft to go around the boiler. so consequently there was no shortage of cogs and chain going spare. I just needed to make a brass bushing to fit the sprocket to the servo. Regards, Gary.