I dont know what it is called. I have used the search feature to look for previous threads for this. I am sure that the 28 people that has looked at this thread knows what this is. You could patch me to a previous thread or website. Will no one help a newbie?Inexperience here. What is the stuff that looks like it is leaking from the bottem of the woofer. I have saw quite a few pics of old JBL's with brown sludge looking stuff coming from the bottem of the woofer esp. on eBay. I know its not supposed to be there. What does it do to the woofer? Is it worth repairing?:dont-know