I've a 27" JVC AV-27820 TV that has a band of lines running across the bottom. The lines vary in width but are generally thin and dance up and a bit withinthe band. The band started at the very bottom, but has expanded to fill up the bottom quarter or third of the screen over the last few weeks. The only other relevant fact is that jiggling the power cord can reduce or eliminate the band temporarily, for a few second to a minute. If I had to guess, I'd say that It looks like vertical height adjustment is too great, but of course there is no vertical height adjustment on the TV.
I'd appreciate any idea on how to fix it. Needless to say, going to a repair shop is out of the question. It would cost more than the TV is worth.