The symptons you are describing are due to a bad convergence IC or chip. They do just what they sound like they do, they converge the colors and lines into one picture. These can be replace by yourself if you feel qualified and have some high voltage experiance and soldering experiance but probably should be left for a repair tech to do this. The repair in home can run around $350.00. If you want to repair this set yourself, I have some instructions below that will be a help to you.
While it is not a very hard repair, this repair can be a bit tricky. If you have a 45W soldering iron, solder, solder wick, and heat sink compound you can repair it yourself.
When you remove the old IC's, please be sure to remove all of the old heat sink compound, as it can act as an insulation for the new IC's and cause them to overheat. I usually clean the heat sinks with alcohol and a small rag.
There are two and large IC's that control the convergence in a big screen set. Some of the newer sets only have one. If you only have one, it is right in the middle of the set on the center circuit board. They are secured to a very large aluminum heat sink. They will have a part number stamped on them that will start with an STKXXX-XXX, like STK392-110.
Along with the convergence IC's there will also be some associated components that will need to be replaced as well. There are some resistors that are part of the convergence circuit that will be open and need to be replaced. Most likely these will appear charred in the center. If you have an Ohm Meter or a DVM, check all the resistors that are close to the IC's and you should be looking for either ones that have opened or have changed values.
If one of the convergence IC's are found to be bad, I would replace them both, if one has gone bad the other may go soon.I would also advise that the convergence IC's be OEM or better, just because they are cheap does not mean that they are a good deal. I have seen the cheap IC's fail after a short time, even though they look exactly like the OEM IC's. I think that the bottom line is that you will get what you pay for when it comes to the parts. I am attatching 2 pictrures that we all use to help with this, if you set looks like these,then it is the convergence.
You can also try http://www.tvrepairkits.com/ , they do carry OEM or better parts.