I have an ibook g3 600 mhz with dual usb. I recently switched the 18gb to a 60gb hard drive. After I reassembled the ibook and transfered the old drive info over to the new internal drive, i noticed that my display dims but doesn't go black when I push back on it. If i push back or wiggle the screen it dims. I have tightened all the screws and connections I can find. Can anyone give me some help?