Before investing much time in this project, make sure that the power brick is still working. The easiest way is to plug it in, turn on the device, and see if it seems to work okay.

If you have a voltmeter, a better test would be to confirm that the power brick is producing the correct output voltage. Usually there's a label on the power brick identifying the output voltage and polarity. In this case, my power brick produces 18 volts, and the plug is wired with positive lead connected to the center conductor.

To test the output voltage, put the red lead of your voltmeter into the inside the central hole of the cylindrical connector that plugs into your device. Attach the black lead to the shiny metal of the exterior of the same cylindrical connector. Confirm that the output is 18 volts.

If the power brick isn't producing any output, try jiggling the wires to get measurable output. If the power brick still isn't producing any output, it might be toast. Then again, it still might be worth your while to proceed to the next step.