From what I see the CRT is a little weak. Do this.
Run a few days.
After 30 mn turn color all the way down, brite &
pix about 2/3 CW.
Turn green down.
turn blue & red up til you get it as B&W as you can.
With a weak tube dont run the bright & pix too high, it
makes it look worse. Run with auto color off if it has a switch.
With regular use it should last quite a while. It will very slowly
get worse over time.
73 Zeno
LFOD !