So I just picked up a mid 70s svt 810 cab... Everything is in good working order except for the bottom left speaker. At low volumes it produces a noticeable rattle, but when the volume is put higher, the rattle seems to disappear, or at least is drowned out by the actual amp volume. When the rattle is audible (at low volume) I can make it go away by applying slight pressure onto the cone with my hand. If I put pressure on the mounting ring it does not help. It only goes away when I apply very light pressure to the cone itself. Aside from this problem the speaker seems to be in good working condition. Has anybody had similar experiences? Can anybody tell me what might be going on?