TV is a Polaroid 42" 1080p LCD, model TLX-04244B.
It was purchased on 11/28/08, at Wal-Mart, with an extended warranty.
It has developed a horizontal dark strip, about 3 inches wide, about 1/4 of
the way down on the screen, running from one side of the screen to the
other. A technician from the insurance company is coming to check it out on
the 13th of this month.
I think one of the backlights has failed. Is it repairable?

TIA!

*Anything* is repairable. Is it economically worth it? Only your insurance
company can tell you. ;-)

It's probably not a backlight. Can you see video in the dark band (look very
closely -- shine a bright flashlight at the area to help you see)? If the
backlight has failed you should still be able to see video in that dark band.
If not...

Your LCD display is probably bad. The display is made up of wide bands (about
3" -- depends on the model) running horizontally and vertically. Each of
those areas is controlled by a driver IC. If one of the driver ICs fail you
get a dark or light band (horizontal or vertical).

This PDF has some symptoms, causes, and fixes:

http://preher-
tech.com/Documents/LCD%20TV%20Display%20failure%20symptoms%20and%20po ssible%20
causes.pdf