Dim screen on my laptop

[beyonddc]

I've an IBM T20 Thinkpad. It's about 4-5 years old.

The last 2 years, I been having problem with the LCD screen. It will get dimmed all of the sudden or dimmed when I first boot the machine. But I'm able to regain the color after folding up or hitting the lcd screen softly.

Finally, the last couple of days, the trick that I mentioned no longer work.

I did a little research, and I see there're 3 possible things that I could look into.
1. Invertor
2. Backlight bulb
3. LCD cable (cable connects from the lcd to the motherboard)

I'm not sure which part I should get, because I don't know which part is not working. I'm just wondering base on the scenario I provided, is there anyone know or take a good guess which part went wrong?


Thanks!!