Not sure if Trinitron CRT worn out, or if it can be restored

[dontdoxmeman]

I have two Macintosh Color Displays (M1212). These monitors have Sony Trinitron CRTs inside. One of them is still pretty bright and sharp. The other, when I received it, was quite dim even when I turned the front knobs up. I eventually took it apart and adjusted the G2 to where the brightness was decent enough, but increasing G2 as I did causes the screen to get a soft focus. I have the focus potentiometer turned as far as it will go, which does improve the focus a little, but it just can't get anywhere near as sharp as the other monitor.

Rather than go down a wild goose chase replacing capacitors, I'm going to swap the tubes between monitors to try and confirm that the tube itself is the problem. But regardless, does anyone have any last-ditch ideas for squeezing a little more life out of this Trinitron? (CRT rejuvination? Modifying the board to increase the focus voltage?)

 

[NJRoadfan]

Its likely an issue with the focus circuit off of flyback transformer (or the flyback itself). Age and heat take their toll on components.

 

[dontdoxmeman]

As an update, I tried hooking up the board of my better M1212 to the CRT from the worse one, and after adjusting all the convergence/etc I still couldn't get the focus any better than it was. I'm thinking this may just be a high-hours CRT. Maybe some day I'll try recapping the board, for now I'll just use the nicer CRT.