Thanks for using Just Answers, I can help you today.
There is a temporary fix for the problem, but it is an indication that your Tv needs major repair. The temporary fix is to adjust the G2 screen knob unti the lines go away. It is a delicate adjustment and if you get it wrong the color of the Tv wont look right. You have to take the front speaker grill off and access the focus block behind the front panel. Then turn the correct knob that controls the blue G2, it's labelled SCREEN and each color has one. If you touch the wrong knob, you could screw everything up so watch out, don't touch the ones that say FOCUS. Once you find the correct knob, turn on the Tv and adjust it down until the lines go away. Here is a good website/thread for research- http://www.avsforum.com/avs-vb/showthread.php?t=469118
If you need further assistance please reply here. Don't forget to click the ACCEPT button if you find this information helpful, and remember that the average price of an in-home Tv diagnosis is $125!
It's not a board that's failing, it's the CRT. Repairing the CRT is way too difficult and expensive to be recommended. And if the Blue is going now, the red and green might be failing soon too. Sometimes they aren't available to buy so they need to be pulled out and sent to a place that rebuilds them. Then re-install into the Tv. That's not the hard part. The hard part is re-aligninment, which can take an experienced tech hours and hours. I really suggest you live with it and start shopping for a new Tv. Sorry for the bad news.