From my personal observations owning those speakers, it is hightly probably that the surround of all woofers are beginning to disintegrate and one of them has disintegrated more than the others, but all surrounds should be looked into and most likely need replacement. Even the one that buzzes might still be repairable by merely replacing the surrounds. You can most likely make a judgement upon removing the covers and observing the operations of each speaker one by one.
Allison One : woofer replacement
Need some advice as to where I might find a compatable replacement for the woofers in an original set of Allison One speakers (patent pending, must be early '70s.) Not sure of the specs but looking for something that is reasonably affordable, the right fit, and as close to the specs as is possible for a proper sound match. I've got three out of four that still keep on kicking but one has this obnoxious buzz. They just come along to rarely on eBay anymore. Thanx