First
Check the elevators are even with each other and move equal amounts.
Then check that they are connected firmly to each other and not broken at the carbon joiner. My has broke twice from inflight abuse.
I have many flights on mine and like it very much.
I have noticed that the harriers have a lot of wing rocking but I think that may be because of the rounded wing leading edge.
Hovers a good but the plane is really effected by the wind. If there is even a slight breeze it is a handful to keep in one spot and yes it likes to fall over on it's back! Maybe because the battery is so high up in the top of the canopy.
I think its more of a pattern plane and a 3d plane but I like it just the same!
Rickc