Retrace lines are a common problem in 1940s and 50s sets, and do not mean that the set is maladjusted. There is different signal content in the retrace interval today than when these sets were designed. Various circuit modifications can be used to improve the situation. Here's an example of one of the more complex, but very definitive, cures for this problem:
http://www.antiqueradios.com/forums/...ic.php?t=86186
Often a simpler modification of feeding a suitable sawtooth waveform from the vertical deflection circuitry through a small capacitor to either the cathode or grid of the CRT will work pretty well. If you search on "retrace lines" at ARF (and maybe here too), you can find information on some of the simpler fixes.