On a Brooks saddle (B66 in this particular case) there's a fat-headed bolt that runs vertically from the lower rails and into the adjuster carriage. If you look at the saddle from underneath, you'll see its head as the big round thing between the two long rails at the bottom of the saddle. That particular bolt on mine is loose. Is that supposed to be so? It's not terribly loose, but when I'm not on the bike it does allow the saddle leather and adjuster parts to bounce up and down somewhat. Is that something I could tighten by hand?