have a 1979 mooney 201 which came with century 41 auto pilot from factory. auto pilot has issue with altitude hold, gets pitchy, only holds altitude for a few minutes at a time, then cannot hold the pitch at proper attitude, then it pitches down, the aircraft loses 300 -400 feet or so all at once, and at that point i have to uncouple auto pilot. have had brain box sent to auto pilot central in tulsa, they say nothing wrong with brain box. have no idea what to do about this, most shops will not work on this brand, aircraft based in denver,colo.