I agree with cutaway on the rib repair, add a servo ( second picture), nad before covering, remove all the covering and sand! Looks like it has been recovered at least three times. I dont believe the leading edge has ever been sheeted on this particular wing, the wood at the leading edge of the ribs would be thicker to accomodate the thickness of the sheeting. sounds like your doing the right thing by being trained, good luck with the repair!