Unfortunately there is no practical service for these. Even with the prior repairs, the tv is significantly past its service life, there are no parts available for them, and labor is not cost effective, as you've already experienced. Most techs won't work on these tvs in the first place or aren't qualified to do so. While it was a nice unit when new, its time has passed and it is worth no further investment. You would easily pay double to fix it at this point (even to try, which may not help) than you would to buy a brand new tv. Further, even if you fix the current issue, other parts are so far past their designed lifespan that it will continue to have more and more failures.
Your best option in this case truly would be to move on from it and purchase a new flatscreen tv with a warranty.
That said, I can help find a repair shop, or recommend replacements, if you'd like.
My apologies for the news.
If you have any other questions, just let me know. Otherwise, please take a moment to rate my service as this is the only way I am credited for my time. Hopefully I have earned 5 Stars but if not please let me know what I can do to ensure you are satisfied. I also invite you to contact me directly with any future support needs at http://bit.ly/1QwLxGh and ask for Nathan.
Thank you, ***** ***** a nice day,