The Airpath Compass on my 1979 231 was leaking fluid. So my local shop got a repair kit and replaced the gaskets and fluid. I can’t recall how accurate it was before, but as soon as I got it reinstalled I noticed a problem. When he placed the compass back in the plane it was 30 degrees off when facing north, and the adjustment screw would not compensate for it. The compass is relatively accurate outside the plane(when not installed). My portable compass also showed the same deviation when placed