Insignia 32" TV Thin line across scr...

The original white line problem was caused by improper adjustment of the vertical size for which there is an internal adjustment. The current problem could come from two different sources, one an adjustment again, the other from a capacitor that is losing capacitance and gaining losses; = sick.
If you are fortunate enough to have a surviving TV repair in your area, none of these problems is expensive to find or correct.
Don't be surprised to find the only TV shop operating out of a messy garage since those of us doing this kind of service are dying off and the price one can charge for labor has shrunken to the point that a real business address is too expensive to have.