Lets see, the flyback failure even though you would lose video, you
were actually losing high voltage, hence the blank screen. That was
and is a totally different failure than what you have now, which is a
worn out picture tube.

Given that you acheived a good life of 4.5 years out of the tube, video
blanking is not uncommon. It is possible that when the flyback was
replaced, the screen voltage was not quite adjusted properly and the
G2/screen voltage needs readjusted. A mis-adjusted G2 voltage will
give the same symptom over time as a weak picture tube.

If the tv were run for 12 hours a day average for 4.5 years, that is
20,000 hours which is the typical life of a picture tube.

No sense having the tv picked up. The screen voltage can be adjusted
per the service manual in home. The only thing that is needed is a
good o-scope and an isolation transformer. It can be adjusted by eye,
and a multi-meter if the tech has enough experience with doing that
adjustment on a Sony set.