Aileron input
There was one additional factor that occurred to me - with flap out I had to add left aileron to fly straight, which makes me think there is an imbalance between left and right flap, more left then right. I’ll talk to my engineer about adjusting that. Thanks for the moderator’s reply. All slow flying was above 3000 feet except for circuits which I fly at Saftey speed as per the POH.