Sounds like there is an issue other than the woofer. Could be a defective crossover. You should send the whole QS8 back to Axiom for diagnostics and replacement. There is no way in hell a surround speaker should be shaking like that especially with a crossover point of 80hz. What kind of source material is going through the surrounds?

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne