We were advised by Opal to change the bearings on our 40 after about four years – which we did but I’m not sure it was necessary as the problem reappeared soon afterwards. Our cure lay in the lubrication of the plastic lined conduits through which the cables are routed. Whitlock in fact recommend that the cables should be replaced every 3-4 years but it is wear in the conduits which cause the trouble. Also, check the retaining collar on the top of the rudder post – if the locking screw has allowed the collar to loosen the post will have dropped thus causing the quadrant to become misaligned.
Hope this helps.