Bad Coiled Cable?

This is an unlikely failure. Run the checks described in Bad Speaker? and Bad Microphone? and you should be able to isolate the coiled cable using a meter, or simply find a MIDI cable and plug it in first to see if it's the cable. A MIDI cable is a musical cable used to connect keyboards and such to computers. It should have all 5 pins wired. They are available at most music stores and many electronic outlets, but a meter check is less costly and more informative.