Hey there garcianc2003 -- I just noticed your reply.

I wish I could say I'm glad I'm not the only one experiencing the rattle, but, unfortunately, your discovery only confirms there's a problem with some of the LFM-1's out in the field.

Harking back to when I first discovered the problem, I tried putting my ear up against the cabinet to see if I could locate a particular trouble spot on or in the sub. Like you, the noise seemed to come from inside the sub -- particularly near the amp side.

However, it invariably went away when I pushed down on the plexiglass top. And so, as my orignal post described, I was able to eliminate it by placing a few VPI Magic bricks in that area.

Since then, I wound up relocating one of the bricks toward the center of the sub top -- so the current configuration is two bricks at the rear, one roughly centerpoint.

If I have a chance this weekend, I'll snap a couple pics' of my sub so you can see exactly where they are located. If you feel inclined to experiment with some dampening, it would be interesting to see if your rattle points are in the same areas as mine.
Outlaw 970
McCormack DNA-125 (mains), Emotiva LPA-1 (surrounds)
Quad 11L (F&C) Wharfedale (R) LFM1 (Sub) w/ SMS-1
Squeezebox -> Behringer SRC2496 -> Musiland MD10 DAC
Sota Sapphire; Marantz 10B;
Video: Hitachi 42HDS52A; Oppo 971H
System Pics