If you want to repair the 501 I would get the correct replacement part from Bose. The crossover and cabinet are designed for that specific woofer and a generic woofer would probably not sound right. Despite criticisms of Bose, I think even they engineer the speaker enclosure and crossover to match the woofer. If their replacement part is priced totally outrageous, then I would consider a generic replacement part or scrapping the speakers.
