Removing the stero
 

How do I remove the head unit? I checked all the speaker wires, and they seem to be fine, the left speaker was working on and off (depending on road conditions) but it only does not work when the CD Changer is playing, but if you switch to radio or the cd player, both speakers work just fine, the conection from the cd changer seems to be ok too, so I'm guessing...the conection to the head unit?
Thanks guys

Marco