My Autohelm ST4000 wheelpilot puts out incorrect compass headings. It hasn't been used in quite a while and I thought maybe the compass was stuck and might free up after some use but that has not happened. It does change readings but never correct. I have recalibrated but doesn't help. When I engage autopilot I get a message "no data". I am assuming that my fluxgate compass is bad and needs replacing. Any thoughts from anybody about this?