Raymarine SPX 10 compass problem

[gauvins]

Three years on the hard, back in the water. Found out that our pilot is not working as it should. It senses North slowly making 360 degrees turns, irrespective of our heading, i.e not responding to the fluxgate compass. I've opened the unit, and found no apparent mechanical issue. Tried to measure impedance and got no meaningful reading. We've ordered a replacement compass.

In the meantime, if this (slowly turning heading) is a known problem with known fixes, please let me know. I've googled and found fairly similar symptoms, but nothing definitive.