Why is my screen really dim?

Harry, that does sound like your backlight. There are a few parts that can cause this. First, the LCD. It sort of functions as the light bulb in your house. Second the 6R8 coil which works like the switch and third the IC 109B. Of course this is in simplistic terms, but it should give you an idea. I would start by replacing the LCD, and then work backwards. The LCD is the easier one to change since the coil is soldered onto the logic board as well as the IC. The coil is easier to change than the IC:). Anyhow, for the LCD check this guide. For the coil check on here. Hope this helps, good luck.