DeadSticker

I am not sure of your theory of putting your hardwood dowels so far into the wing. They shoul be mounted as close to the hinge line as possible and then the control horn is trimmed back to be even with the hinge line.
By doing it the way that you did , the servo arm will have to move further than if the control horn was mounted on the edge.
You want to get the throw you need with as little movement from the servo arm as possible. For correct mechanical advantage the servo arm should be the same size or smaller than the hight of the control horn.
I hope this helps.