Polk Audio RMDS-1 system

I have this Polk Audio RMDS-1 system and I think the subwoofer unit has gone bad....can I replace just the subwoofer unit without having to buy the entire system again? I am pleased with the system but the sub unit started acting up and now it is not responding at all. The fuse is good and receiver seems to be performing OK but no sound in any of the speakers from any source....mute is not on.
Thank you for your help.

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