When your tv picture comes on about a half inch tall, until it warms up, is it probably the tube?

If it's not a tube, then it's probably a capacitor. If it's the tube, it will be expensive to fix because there's almost no tubes anymore, tubes are super expensive. If it's a capacitor, it will cost dirt nothing to fix. The process for the capacitor is to find another one that's the same rating as the one that needs to be replaced, then the one in there needs to be removed, and a new one just carefully soldered in its place.