I've not heard of this, but it seems more likely to be a problem with the plug, not the cord. Probably time to take it in.

Crap.

If you have a voltmeter (or multimeter, etc) test the output voltage. The brick itself should indicate the output voltage in a printed or plastic-stamped label, usually 16-20 volts DC. If not your computer should have the input voltage listed on it as well.

If there's no voltage at all or a steady-state current of the wrong voltage (usually less than the specified voltage) the brick probably failed.

If you can manipulate/bend/futz the cable and it occasionally gets full voltage, it's a crack/break in the cable and is easy to splice.

If you're out of warranty/service contract and it's non-replacable and you can determine it's a break/short in the cable, splicing is pretty easy.

Note that many/most modern laptop cables on the DC segment (the part between the brick and laptop) they use a sort of coaxial cable, with one conductor (or even ground) as a braided "jacket" and the other conductor(s) inside of this jacket. This means you'll have to strip the outer jacket, pull back the outer conductor away from the inner jackets, strip just part of that, and go from there on your splice.

And simply twisting the wires together and taping them up nicely is usually enough. The voltages put out by laptop bricks are low voltage and relatively low amperage - not at all likely to start a fire or otherwise injure you.

Thanks, loquacious! I'll try that.

while i agree with loquacious's theory, in practice pauli's cable (12" powerbook) frayed near the plug and started sparking and smoking one day. so it's not as safe as you might expect.

Sparking can and will occur with low DC voltage, voltages below 24 volts are not enough to overcome the resistance of your skin unless you are very sweaty or you have an open wound and it gets in contact with your inner meat. I've gotten shocked by 24 volts DC at work when a wire slipped out of my fingers and into a cut. Didn't hurt so bad really... not like household AC current at all.

while i agree with loquacious's theory, in practice pauli's cable (12" powerbook) frayed near the plug and started sparking and smoking one day. so it's not as safe as you might expect.

Well, yeah. You can start a fire with a single 1.5 volt battery if you know what you're doing.

But a properly spliced/isolated DC cable isn't at all likely to start a fire. Frayed, actively short-circuiting cords pulling ~20vdc at about 1 amp are another story.