Approximately 2/3 of the screen is dark. this started about six months ago and is progressively becoming worse. when problem began the screen would recover to full brightness after it was on for 30 minutes, but now remains dark

try first with the led strips noo need replacing t-con

There are two sensors. One the camshaft, the other redundancy. They look exactly the same. I could not find them until I printed a drawing of my rio, and then it took ten guys scratching our heads to find it. Just don't put them in backwards; they do look the same.

Please find if your piano
is vibrating more than before
If it is not problem
THen go to nearest repairer
if it can be repaired you must repair it
And it doesnt YOU have to change It !!!!

It looks like DLP chip is failing. It is installed on DMD board that in turn belongs to optical engine. Issue should get progressively worse. If you look at screen up close - you see that "tumbprint" consist of little small dark-gray squares, some of them flickering.
Cheapest solution - to replace DLP chip. instead of replacing whole optical engine.
This repair have to be confirmed (by running test patterns in service mode first) and done by professional.
Repair could cost aroung $400.
During procedure I would recommend to turn ceiling fans and other air blowing devices off. Single little dust speckle landing on the chip surface will ruing all effort and same amount of labor have to be applied yet again just to get rid of it (been there, done it).
Good luck.
Russ.

Adjust video settings:

1. Press Wega Gate
2. Select Settings
3. Highlight Video
4. Press + to select
5. Adjust/increase the brightness.
6. Press Wega gate to exit.

If picture is still dark, you need to replace the lamp again. Sony recommends that you replace the lamp:

1. After approximately 8,000 hours of use.
2. When the screen becomes dark or the color becomes unusual.
3. When the lamp indicator on the front of the TV flashes.
   

Turns out it is a defect in the phone. I traded for another Lotus; it doesn't happen to all of them and hopefully it won't happen with my new one.

Not all replacement parts are good. I would guess that the new ignition switch is bad. Its also possible that the wiring harness is loose where its connected to the ignition switch. You could try jiggling the wires.

I had the same problem with my 42pc3d, it had a new power supply put in it as a fix. Call LG Customer service.....They are very good and will fix it even if it out of warranty usually.

I THINK YOU HAVE A PROBLEM WITH DEFLECTION - I SUGGEST TO REPAIR IT BY TECHNICIANS - THAT TV IS UNDER
WARRANTY - DELFO

this problem is due to 1 not proper voltage on crt terminals 2 check video output supply voltage 3 check luminance section of chroma ic 4 if tv is very very old than there is a possibility of crt getting weak