Now I attach the Walnut fingerboard. I plane the glue-side flat. It takes a bit of back and forth from both directions. The board seems to have fibers that are not uniformly laying in one direction, like a petting a dog with hair that sticks out both ways so you can never pet it smooth. But I get it down and get some wood ribbons from the plane. If it's some interest to some, this is a $15 plane I bought new a year ago at HF. If there is any poor planing it's all in the technique.