[iBook] iBook screen problem

[Steve Stuckwisch]

I have an original (white) 500 MH G3 iBook.  It has given me and then  
my wife many years of great service.  Recently it has developed the  
following problem:

When first turned on, if the display is opened past about 50 degrees,  
the back light goes out, i.e. the screen becomes dark.  (At least I  
assume that is the problem. If I hold the screen in bright ambient  
light, I can just see what is on the screen.)  After the computer  
gets a little warm, I can open the display to about 80 degrees before  
it becomes dark.  If I close it back to the original position, the  
screen is again visible.  About 80 degrees is the most I can ever  
open the display without darkness.

I'm willing to take the computer apart to fix the problem (I used  
this as an excuse to buy a new MacBook, which I got today.)  Does  
anyone have any ideas?  I.e. what exactly is wrong, what should I  
look for (a loose or pinched cable, bad light, etc.)  Any previous  
experience with this problem, guidance or a point to a web site would  
be appreciated.

Steve S