i agree with pat: the thing could bend more in the outer parts of the limbs...i know you might not want to reduce the wood anymore, because you lose draw weight that way, but it'll get your tiller on track: this will make more wood available for work, and help reduce set. Set is inevitable in a board bow if only the first 1/3 of the limb bends: all the pressure is put there, and this weakens the fibers, and they take set. If it were me, i would get the limbs into a more efficient tiller, even if it drops the bow to 30# or so, and then glue on a 3/16 strip of hickory to the back. This will bring up the draw weight and also help the oak (more brittle than hickory) to survive.