While the tubes may be flat when they have a lot of hours on them, not infrequently blurriness is also caused by things having drifted out of alignment. Finding service docs is another matter though. (And of course some care is required with devices having some nice high voltage inside.)
Greets from Team "85 Hz is not enough"...
CRT's dim after a while, while otherwise still working in the same way. That's the biggest disadvantage of the CRT. On the other hand, LCDs (TN panels, especially) tend to have poor blacks, low viewing angles, and they tend to have image tearing a LOT more than CRTs.
CRT's are arguably more ideal for graphics, due to their color accuracy, and the maturity of the technology. The slight shadow mask, or aperture grill blur can be enough to make pixel-size defects look better. There is an advantage to not seeing every imperfection, especially for gaming. CRT's also have no difficulty with viewing angle, due to the glowing phosphors of the display.
LCD's are better for text, at least, at the native resolution of the monitor. The crispness that LCD's have make reading the subtle letter clues much more convienient. It's also easier to put an LCD into a vertical orientation, although TN panels do not work well for this purpose, the MVA, VA, or IPS panel types are much better for this purpose, because the viewing angle is larger.
That was one of the main things that ultimtely drove me away from CRTs; the maintenance. When convergence controls wouldn't work (as well as you would have hoped), you had to sit there and try playing with the deflection yoke to correct some misalignment. Hopefully, you would be able to correct it with the focus controls, but amost always, this wasn't the case.
The things we do for picture quality. I am so glad digital displays came along.
Wasn't that the purpose of automatic degaussing?