How do I get the flouresent light tube out to repace it?

Video output section circuit have the fault. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

if this is the one with the flouresent lighting (soft blue glow) , this means the tubes are going bad , sorry only way to fix them are to replace the instrument cluster , the tubes are built inside

The tube that doesn't light is probably burnt out, buy a new one and install it, if it doesn't light, then you may have a ballast problem if they are flourescent bulbs.

An lcd tv has to have a light source behind it to see the picture. Older ones have flouresent tubes. Newer set have light emiting diodes(led). You need to determine if the backlight is turning off or is set loosing signal. If you press the menu button on the Insignia remote does the menu appear on the screen. If not hold a flashlight on the front of the screen. if you can slightly see some video the the back light is off. If the menu shows then check the signal source. If back light is out the replace the inverter board.

Do you have back lighting. Shine a light on the screen. If you can barely see a picture the set has no backlight but video is good. This would rule out the main board. Not shure if this set is LED backlight or flouresent tube back light. If flouresent tube check for voltages to inverter board. 24v or 15v. They are marked on the board. If voltages are there likely inverter board. or could be power brd. Check pricing on new tv.

ballast--- -usually a ballast transformer used in flouresent lights to turn 120 volts ac into 2000 or 3000 volts ac at a lower amperage. the ballast transformer has 4 nuts ,one at each corner for physical mounting .2 wires for the ac line cord and 4 wires for the flouresent tube. wires are connected together with wire nuts that can be pulled off the wires while unscrewing the wire nuts.
make a picture of what color wires go where,take wires off one at a time and make pictures. the wires are not interchangable and must go back exactly where they came off from or the unit will never work again.
many ballast transformers have an electrical diagram showing where the wires go. you may need a magnifing glass to see it well enough read it. Please study the diagram and understand it before you begin disassembly.
WARNING: You must make sure that the electriic cord is unplugged or the circuit breaker on the OFF POSITION
with the electricity on ,you can be electrocuted by either the 120 volts ac or the 3000 volts ac that means crash,burn and fry.
so de-energize first.
The replacement ballest must be rated for the wattage of the flouresent bulbs ,the length of the flouresent bulbs and the diameter of the flouresent bulbs. that are in the lighting fixture. the flouresent bulbs also have their own make and model numbers.the model numbers of the bulbs are standardized throughout the industry. The model number of the flouresnt bulbs that a ballast will work with is on thw ballest sticker, on the cardboard box and on the directions.the salesman in the flouresent ballest [lamp] section at home depot or lowes should also be able to help you.

There may be near by interference, example flouresant tube. Move the monitor in different locations to see if there an improvement.

even if there is power at the sockets, ballast may not have power to fire off the lamps, how old is this fixture, and you need to replace the ballast same as in fixture, if you replace ballast make diagram of wiring so you can rewire it like it was wired from store.

look for a fuse inline from battery to managment box.relace fuse if bad it should be in a small plastic tube possibly white in color.

The "bulbs" in LCD's are CCFL tubes. Similar to the long flouresent lights you see in office buildings etc.
If they are blown, then they don't flicker.
Chances are the inverter circuit, what powers those tubes, is failing and should be looked at by a qualified technician.

Hope that helps =)