[wiseguy]

try this
Leave it on for about 5 mins or so, lens capped
after warmup remove lens cap, set zoom on wide, but do not aim at any bright light but just something in the room, looks for a control on Deflection or HV board called "BEAM, or Beam Current" turn very slowly clockwise till you start to see more of an image appear, and stop to where image stops Flare green in highlight areas.
also if tube Focus has been messed with the image will always look green, so don't touch that control as these sort of interact with each other.
Tube focus (not lens focus) is adjusted for best focus at start of center of image and when "minimal Green Carrier" is gone, but the perimeter of the image is touchy to align, this is where the Horiz, Vert sawtooth parabola adjustments take care of that.
but I would only adjust Beam and hopefully no one has messed with any of the other controls