If he was given a pair (free), then they are definitely worth the expense to fix the woofers. They still fetch $3000 on the used market, if they're in perfect shape. Go the B&W website and get this Adobe brochure.
http://www.bwspeakers.com/downloadFile/speakerModel/DONE_-product_info_808.pdf
I would contact B&W about suggestions for replacing or repairing the woofers. You could also contact Miller Sound Labs in Pennsylvania about repairs.