If what you are trying to say is that you have a 1/4 inch horizontal line across your screen, this means that something in your vertical deflection circuit has failed. This could be the vertical oscillator, the vertical output processor, the vertical coupling capacitor, or the vertical section of the yoke transformer.
If what you are talking about is a vertical line from top to bottom then you are possibly talking about a failed horizontal section of the yoke transformer.
Why so little about the horizontal
section of the yoke? That is because if the horizontal section fails completely
then you would lose high voltage and no line would be present because you would not have raster (screen light).
In any even check the yoke transformer first. Then work back from there.
I hope this helps,