This is a very easy (for me) thing to advise on.
If colors are skewed and or a bowed picture you will need to replace the two STK-392-570 convergence chips this set uses.
Total parts cost on EBAY--I can tell you the seller there that I use--will be under 25 dollars.
I have start to finish, step by step instructions for this repair in the model set.
What it entails is getting the middle circuit board out of the set correctly, replacing both chips and putting the board back.
This does involve a little soldering and some skill with hand tools but I have done it hundreds of times and helped many people here do it.
The instructions (which I can post here and are free) tell you everything you will need and exactly how to do the repair.
See attached typical convergence photos that show how this problem looks. No two sets will look the same but there are reasons for this problem.
The chips are about 2.5 inches wide X 1.5 inches tall and the metal on the back of them is coated with a white grease to transfer heat to the metal they are attached to--after 5-8 years the grease dries out and one of the chips goes bad.
Let me know if you want and I will post the instructions here for you.
If the information I gave you or the photos told you something you did not know, rate this solution as very helpful as I do this here for free.
THE TWO CHIPS WILL LOOK SOMETHING LIKE THIS BUT HAVE THE STK-392-570 NUMBER ON THE FRONT OF THEM
LET ME KNOW IF YOU HAVE ANY QUESTIONS OR WANT THE FREE INSTRUCTIONS.