I've recently acquired 2 Brooks saddles. One is like new, used but very clean and a tad flexible. The other is weather beaten, surface cracks, a fair amount of flex; but I believe there's life left in it. I am using the Proofide leather dressing. My question is on the adjusting nut. How tight is tight enough? They both have the threaded rod near the beginning or starting end so I assume neither has had or very little adjustment.in their life.