I was getting a "bonk" sound and the sound of a vibration on most of my rails on a 7-foot Valley when I had to hit the rail head-on, even with a new set of rails. At first I thought I didn't tighten them enough or some cloth or staples were not letting them seat right?that wasn't the case. What I found was 5 out of the 8 corner bolts were a few turns loose. These are the bolts you can get at from each pocket with a 9/16 wrench. I know the table mechanics know this happens, but I never saw it on this forum. I don't know how often it happens on Valley's, but by rails sound and play much better now. Johnnyt