Sounds.. (pun intended) like the "Voice Coil" is "Binding on the "Post" This is fixable, for a price, they can be "Re-coned" but it may be simpler and easier to simply buy a replacement speaker and re-install in the case. Speaker are relatively inexpensive, and are easy to put in, there are only two marked wires. Radio Shack, or eBay might be good places for speaker.
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Sounds.. (pun intended) like the "Voice Coil" is "Binding on the "Post" This is fixable, for a price, they can be "Re-coned" but it may be simpler and easier to simply buy a replacement speaker and re-install in the case. Speaker are relatively inexpensive, and are easy to put in, there are only two marked wires. Radio Shack, or eBay might be good places for speaker.
1.Your speaker cone is rupture.
2.Replace that subwolfer or speaker.