You need to identify the problem with it. Get a hold of a Digital Multimeter, and put it on Ohms, check the resistance across the coils. If they read some ridiculous number and not the specified resistance, then the coil is blown. But if it reads okay, there may be something else to troubleshoot. If it is blown, it will require a re-cone. The only subs I am familiar with the re-cones are Image Dynamics, cause they are stupid easy to do. But there is typically someone on here that knows how to do it.