I have a Viewsonic LCD monitor lying unused for some time now. Today when I connected it, its showing a block of vertical lines which makes it almost impossible to use.
I used VGA cable to connect as I have no DVI cable. I use the same cable and GPU for my other monitor too for which there is no such problem. So its something with monitor.
Don't try to open the LCD panel to swap parts. It's sealed to avoid dust coming inside. Find a working used iBook G3/G4 12" LCD panel and swap it in the display assy. If you want less trouble buy a used 1.33 ibook G4 12" display assy and only swap the complete display.