Any help is appreciated here. I have a 27" JVC tube TV that just started having this problem. When I turn it on there is only a thin horizontal line across the screen. Then it will start trying to go to full screen, flashing between the horiz line and full screen. It does that for a few minutes until it stays on full screen, flashing off only occassionally. Any thoughts on what this problem could be?
Dave

Try to resolder the vertical IC, and check nearby caps.

Dave,

It might be a bad solder joint in the vertical section. When the set warms up, the solder joints make a good connection and the screen expands to full vertical height.

This is a simple fix for any tech.

Also replace the electrolytics around the IC there will be one which has the + to a diode and to an IC pin that is crucial, usually 100uF 35V use 63V.