Before surgery/replacement try rotating the faulty woofer 180 degrees.
The woofers also need to be sealed to the cabinet (it's a sealed system and any air leakage will increase the woofer's travel distance/excursion).
Once snug the bolts should be tightened systematically and gradually (like tightening up the oil pan on a car).
I don't know what would be good to seal them with (RTV silicone?) but others here should know.
DeKay