I cant figure this thing out, im new to auto pilots. It worked ok last fall for about the first 50 hours i had the boat. This year it started messed up & hasnt gotten better. It seems the compass cant get its bearings, sometimes it will hold bearing but if i try to adjust with knob or arrow keys its goes wild & the compass reading goes round & round. Sometimes it will be holding path alright then veer port or starboard off course & still say the heading is the same. Also compass never matches gps or actual compass always at least 7 degrees off. Any & all help will be appreciated is there something ican do on the menu that will help this. Compass calibration doesnt work just keeps going & going. Is it the compass? Perhaps unit is too old & i should replace?