We had a F172H ( a '69 French-built model) which would either fly half a ball out hands-off or if you adjusted the rudder tab for slip-free flight, needed about 2-3 lb down force on the column. The engineers tried adjusting the cam, then adjusting he incidence of the flaps but with no discernable result. In the end, a Club member solved the problem by landing it on the noseleg. Surprisingly, it didn't snap off, but pushed the firewall back into the cabin, distorting the floor as far back as the front seats. Even that didn't do for the a/c as someone rebuilt the front as a project. What finally did for it was a winter storm that flipped it onto its back.
Sad, really, though it was old it was a good and faithful servant with a lovely 6 cylinder Continental, much nicer than the brash 4-pot Lycoming in my view,
TOO