Quote Originally Posted by Mark_IDT
I pulled the driver it's rattling from inside the magnet structure. Almost sounds like a woofer that isn't crossed over with sounds from the highs coming through.
Possibly a blown voice coil. It will still output sound, but it will typically be at a lower output and sound distorted compared to an unblown driver. Time for a new driver. Might want to contact your nearest Paradigm dealer and see what they can do for you short of ordering a brand new (and potentially expensive) woofer from Paradigm. Maybe they have some spare drivers available.

If it's not distorting and does not sound audibly different from the other drivers at lower levels, then you might simply have something loose inside the driver.