My recommendation is, before you spend on the circuitry of the subwoofer, try localizing the problem whether it is mechanical motor problem from the driver or the amplifier. By doing so will help in deciding your next step. Try disconnecting the driver from the internal amplifier plate, and use an external power amplifier to power and test the woofer for any mechanical problems. Assuming the Driver is ok and has no problems, I would ask myself whether if I should power the subwoofer via external amplification like a passive subwoofer, eliminating the connection of the internal amplifier, or try to buy a subwoofer amplifier plate to replace the original. There are subwoofer amplifier plates which can be used, but some modification maybe necessary. I hope this helps.