The sub is sold as a complete assembly but you can infact open it up and extract the bass driver (speaker). On mine the foam surround (that suspends the cone) had disintegrated away. Took it to a hifi repair place (not ICE place) and they replaced the foam, no fuss. Popped it back in and hey presto. Now if I were extremely picky I might say the timbre of the bass has changed slightly, might have something to do with different response / rebound rate of the new foam material but its also probably no more than if you buy a brand new sub. No two speakers are ever ever ever identical. And in a week or so I 'tuned' in to the new sound and can't tell the difference anymore.