Personally, I think that Dale Clemens confused the spine-finding issue in his Advanced Custom Rod Building. What you are really doing is finding out the natural way the blank would bend (what position it would twist to might be a better way to put it) if line was strung through the guides and the rod arched severely. I think you would be better off if you forget about looking for subtle "jumps" and just be concerned with placing the guides on the softest side of the blank. That would be the top side when arching a blank on a flat surface while applying downward pressure near its center; or you could say the inner surface of the arch.