Not sure as all the parts are laser cut and nothing has changed with this kit for 3+ years. The wings are built upside down so obviously the slots for the aileron mounts should face up as you have them in the picture. Slide in the wing tube socket to double check that you have these ribs properly oriented. Only the wing tube socket is asymetrical given the tapered wing however the outline of the rib is symetrical so even flipping it over would not matter. The only thing that comes to mind that would offset the rib would be the position of the main spar on the board of which the rib fits over. make sure it is pinned over the plans properly. Other than that just make sure the rib trailing edge rests on the jigs provided. If you have to move them in a little and pin in place.