Wandering Autopilot
I just had the same problem on my C320. When I installed my fluxgate, I used hook and loop with adhesive backing so that I could experiment with various locations. After contending with excessive wandering and looped feedback oversteering a couple of weeks ago, it dawned on me that the fluxgate was the most likely culprit. Sure enough, after having been moved several times the adhesive had failed and my fluxgate was lying on the hull. I stuck it back up and the problem resolved. Next step for me, is to find a better spot than the water tank and mount it with screws, heheheh. Hope your problem is as easy to resolve. If your fluxgate is mounted properly, there is an ohm meter test proceedure on the Raymarine website for testing the flugate. Look in the customer service section where they post tech questions and answers. Choose the 'autopilot' drop down box and type 'fluxgate' in the search query. You will need an ohm meter with a 20 ohm range. If your fluxgate turns out to be defective, and out of warranty, contact me off list. I have a spare.
