Shoot a picture , usually it’s just fine adjustments on the flyback then fine tune from there .

The age of that monitor would dictate it most likely need caps at the very least, and probably a horizontal output transistor ...But what you don't want to do is mess with that yoke or purity rings, because you will lose your convergence and few people do that anymore.

There should be focus and brightness adjustment potentiometers on the flyback which should help you get some clarity and brightness. There's also adjustment pots on the monitor chassis itself for picture size and position. See if your monitor has a pot for controlling the black level, as I would adjust that along with the brightness and focus to dial in a solid picture.

Set up a mirror in front of it so you can see what you are doing...I would seriously consider rebuilding the chassis first, before messing with settings, it should have been good at one point, and something has slowly changed.

It looks like you need to adjust the brightness just a tad on the flyback . The adjustments are very sensitive so you just barely turn it . The mirror trick is a good help . There also should be a separate small adjustment board somewhere for the other adjustments ( width , height , horizontal , contrast and brightness) it truly is a minor adjustment on the flyback and then fine tune with the other adjustment board .

Once they start to drift, adjustment is just a stop gap fix at best, Its been my experience something will give out within 6 months, Usually caps, H/out, flyback, or any combination of the three...In any case be careful messing around with that monitor, they can bite hard, I got shocked by a faulty tube one day so hard it actually blew a filling out my tooth.

That blue looks as if it may be struggling a bit?...a rejuvinator with clean and balance would most likely fix that, (Bk460 or so)...Would totally hold back from a full rejuve (or using a brightner) however, as that cooks the anode and could potentially shorten the life of the tube, But again caps first (at least) would be a good business for longevity...That is a highly sought after tube, Some of us girls might be a little jealous.

I think you would be glad you did, Problem is not many people do that anymore, just finding someone who can even solder seems tricky...There are lots of good vids on Utubes on the subject and the kits are cheap (around 25.00 us) but you want to make sure it is a reputable vendor that sells quality...If Jenn was to call someone, I think my first call would be to Eldorado games and see what they say.