sub problems with mach audio system

i have a mach audio system and the sub is only puttin out a very faint sound and u have to put ur head next to it to hear it. is the amp shot or do i need a new sub?

Look for bad connections to the amp and sub, after that, unscrew the sub form the box and make sure that the wires are connected to the terminals( the two things sticking out of the speaker) If the surro und(the rubber part of the speaker) is very loose, there is a good chance it's shot. Also check battery connection. to test the sub, hook it up on a home theater system and see if it sounds the same

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Ford dealers keep tryiing to sell $250 subwoofer box assembly when speaker is only problem. They do not mention that a kit is available with 8 inch speaker new for a fraction of price. $80. Kit # 4L1Z-18C804-BA