Sorry, no ... it was not a sophisticated fix.
I used a flexible piece of plastic sheet, like a hotel key card, the credit card was too thick and too stiff. I cut the squarish notch in the plastic, the width was just enough to fit the yaw shaft's notch/flat area.
The plastic is used to keep the shaft from moving while you try to rotate the arm to correct the error by fastening it in a bit off position, and screwing the retaining screw at the same time.
I am pretty sure there is another way but it would involve recalibrating or replacing the servo that controls the yaw movement ... a trip back to the factory most likely.