I recently moved and set up my oversized 8' Anniversary in my new home. slate leveled and everything went relatively smoothly. After recovering and installing rails and starting to play, one rail make a thumping "dead" sound when balls strike it, but the balls rebound and it plays as it is supposed to. Anyone know why this is? Did I not tighten the rails enough? rubber coming loose from the rail? Thanks. Doesn't affect play, just sounds crappy.