Tim, sounds to me like the backlight inverter is going out. You want to definitely check on fuses or continuity of voltage supply lines going to the X Board/s, (your case check the X Board) as well as the LVDS cable. Replace blown fuses, connect broken lines, and resolder loose solders. Check on the capacitors on your boards, they may be either loose or popped. Look for any leakage on the boards (looks like a oily sticky substance) and check the top of the capacitors. they should be flat. Any bulging indicates a failed capacitor, The older LG's have the backlight inverter power separate from the power supply, and in that case you will require a new LCD Panel. Very costly, if you can even find somebody who has them for sale. The newer LG's have the inverter connected to the power board. In that case you could try to fix it by replacing the power board. It would be great if besides the model number you could find the Chassis number. It might be possible to get a service manual for you and give you some more specific details for your TV. Hope this gets you started in the right direction. Good Luck.

hi there tim,this isn't really an answer as such ,its just i have the exact same problem and i am wondering wether you actually got your lcd set fixed at all? and how you actually acheived the repair,any info would be appreciated. yours faithfully larry!

my first idea, the origin of the problem is a bad solder somewhere on the (power) board or a back light unit(inverter)(or light(defective))