I bought a pair of used Monitor Audio GX100's and after hooking them up last night I noticed the bass was weak from one speaker. I went and touched the driver and it was very very slightly vibrating so I turned off the system and manually pushed on the driver. It didn't budge at the center and at the edges it only slightly moved but was definitely "pinned" at the center. It also seems that the woofer is roughly at zero displacement, meaning that the driver isn't seized in or out of it's neutral position.
What could cause a woofer to seize in this manner? Is there anything I can do to try to fix it before returning it to sender or purchasing a woofer from M.A.?
EDIT** I should also note that the speaker's box was a little rough upon delivery. Could it seize from a hard jarring?