Does anyone know where to get an autohelm ST4000+ control head. My old ST4000 has stopped working, bad timing as I just installed my new MK II wheel drive. The research I have done leads me to belive that a ST4000+ is backward compatable. I also wonder if anyone knows whether the smart heading sensor that is connected to my Raymarine E120 via seatalk hs can replace the course computer in other Raymarine autopilots