i recently bought a used 10 inch sub from a friend...and i have not bumped it yet so i don't know if its good or not but i noticed that when i try to push it in with my hands it is really stiff and i asked my friend if he just sold me a blown sub and he said no i just have not played it in a while thats why it is so stiff......so now im wondering why it is so stiff ....any answers?????