I am the proud new owner of a 2000 Catalina 470 with a full Raymarine system. ST80 Masterview, 2 ST80 Multiview, RL70C Plotter, Type 300 Course Computer for the autopilot. While cruising this Summer, the Heading Sensor seems to have lost its calibration. About 150 degrees off. On the plotter, looks like we are dragging the boat backwards, so the predictor line is way off, and the look ahead feature on the plotter doesn't work.Today I worked through all the setup menus and can't get access to the compass linearisation or the offset adjustment. The icon on the right button just shows a blank square. Went to the Pilot Calibration section to make sure the Cal Lock page showed the page as Unlocked and saved settings.A call to Raymarine was very unhelpful. He walked me through a couple of things and gave me some resistance values for the wires to the heading sensor (they were all fine) and then everything was no, no, no, and no. No we don't support the ST80 anymore, no we don' have any manuals or information online, no we don't have any techs around here that know anything more about the ST80, and no there is nothing more I can do for you.If Raymarine can't support expensive systems that are only 7 years old, it makes me reluctant to recomment Raymarine or upgrade my system. The heading sensor does seem to work. Values change appropriatly when the boat makes a turn, or when I take the sensor off the bulkhead and turn it manually, And no, there is nothing ferrous near the sensor. The tech did say that the offset value is stored in the course computor. The calibration page on the Masterview just shows a value of ---. I just can't get to it to change it.Long post I know, but there are a lot of important details to get by all the obveous solutions. Does anyone with experience with this situation have any solutions?