just take it abck to where you bought it or contact the manufacturer, cant hurt and should of gotten a warranty. If they wont do anything try sealing it with something as mentioned above and not pounding it too hard
also you should try to figure out why its done that, to me sounds like someones poked something in it or somethings rolled in boot. But hmm the sub cones are stong is on my spl dynamics one
bad luck tbh