Vertical bar on Daewoo Plasma screen

I am getting a vertical black bar on my Daewoo Plasma screen which comes and goes.
We have a 46" LG plasma, with vertical lines in a variety of colors: red, blue, orange, green, you name it. We have 3 lines on the right and 1 on the left. Please help!
(Note: it's actually TH-42PX6U, not 60U.) About 20 months after connecting my Panasonic 42" plasma, I got a persistent vertical black bar with a narrow (1-2 pixel) strip of rainbow color in the middle of that; this bar is just right of center. Panasonic said "sorry, out of warranty, try this local repair shop"; they did all the diagnostics, replaced the one board that it might be (no fix) and concluded it's the ($2000 to replace) plasma panel. (Major kudos to DTR Technologies in Denver, the local repair shop, for only charging me the base $90 service call fee since they failed to correct the problem.) My TV probably has less than 200 and definitely less than 300 hours total; we just don't watch that much TV. I'm quite disappointed - and will appreciate any advice - esp. if anyone has been successful in getting Panasonic to pay attention and address this obvious manufacturing defect.