Barkhausen lines don't affect the sweep linearity either. Jordan has a genuine Barkhausen line here:
down the woman's right (stage-left) ear, down her jacket collar and between the 5 and 7 of the 576 phone exchange. It's very minor in his case so I didn't mention it, and it's not present in his other photos of the same set. As you can see, there's no squeezing or stretching of horizontal sweep around that line. Like Eric said, they're usually dark and thin. They also change with fine tuning and are more visible on weaker stations.
Damper failure lines don't change with tuning or signal strength, and affect linearity of the horizontal sweep. Keep looking around the damper-network circuit.