Hi Jinio,
Thanks so much for your post which guided me towards a fix.
I used the tip of a protractor to remove the snapped of stereo jack from my Powerbook G4.
Gently push the protractor tip into the stereo jack. You do have to exert a fair amount of force and soon you'll notice the sharp point of the protractor piercing the snapped off stereo jack tip. Once fully embedded, gently remove the jack tip whilst simultaneously pushing in the opposite direction of the stereo jack plugs gripping springs and voila it popped out.
Now to see if the stereo out plug still works