Rodney

I'd be more apt to believe you have a slight warp or twist in one or both wings. Get about 10 or 15 feet behind the plane and then have the plane propped up so you can see the trailing edge of both wings. As you sight at the trailing edge, see if you can see the same amount of wing surface on both sides as you raise or lower you gaze at the trailing edge. As you move your gaze, the lower surfaces should all disappear at the same time. Since this is a flat bottom wing, get 4 straight firm sticks of wood and attach one each near the bottom of each root rib and the other two at the bottome of the outermost full length rib and sight from the side. All sticks should line up perfectly, if one or more is tilted more up or down than the others, you have a warped wing. No need for a fancy incidence meter.