OK, first off there is no positive or negative on a woofer. There is a convention that when the positive lead on a battery touches the RED lead on a woofer, that the voice coil moves OUT.
Your quest is to determine the RED lead and you can do that with on old remote battery (1.5 volt partially discharged). Connect both the + and - battery terminals to the woofer and watch the voice coil. If it moves OUT, the RED terminal on the woofer is connected to the positive battery terminal. If the voice coil moves IN, the RED woofer terminal is connect to the battery minus.
Regards,
Jerry