I have an aging Raymarine set up and the compass reading on the ST7000 Control unit is now showing a huge error, about 90 deg out in Standby before I attempted to correct using the Control Unit. However this has now got an error of approximately 40 deg. Before I start making more adjustments has anyone had experience of a rogue Fluxgate compass. The autopilot will hold but is now a bit indifferent in operation. Interested in any theories or testing suggestions to correct or establish if it is a faulty unit.