I have a cbs Columbia 1954 that I recapped works well but upon turning it on soon as the picture shows it has a white line top to bottom 12-6 position after about a minute it’s gone any ideas what or why that would show up like that never seen that in other sets befor

If it were constant, I would say look for a horizontal drive or horizontal efficiency adjustment, but since it goes away after warmup, how about replacing tubes in the horizontal sweep section first. (H oscillator/driver, horizontal output, damper)

Ok well I’ll check these tubes but I do remember I had a hard time stabilizing the horizontal since there was a few mica caps that I have but didn’t change them so maybe they might have to be changed. Thanks