Presario R3000 Laptop Screen Dims

I have a Compaq Presario R3000 and the screen occasionally dims so dark that you can only see the screen if you have a bright light shining against it. Usually if I shut the laptop off for a couple hours it will work properly again, only to repeat the problem after a while.

I’ve read a number of posts that recommend replacing the inverter, and others that recommend replacing the backlight behind the display. Is there a way to tell exactly what the problem is, or how to fix it? Thanks.