Loose driver mounting screws on Velodyne HGS-18

Hi folks, I recently removed the grill from my Velodyne HGS-18 (purchased in 2001), and while the grill was off, I figure I would tighten the 6 hex screws securing the driver to the enclosure. I noticed that all 6 screws were quite loose (by several turns). Anyhow, I tightened them all up, and the bass was noticeable tighter afterwards. I contacted Velodyne and asked them if they have heard on seen this happening on the HGS series subs, and they said no. So does anyone out there with an HGS series sub want to take the grill off the sub, and check to see if the screws are loose, and hence you are missing out on some tight(er) bass. Maybe this is a common occurrence, but that people never remove the grill cover and check, so they never realize it, and have been living with loose(er) bass.