I think on average jugs from the late 60's til late 80's
are lasting a long time. B&W's from abt 1960 on also.
New displays are super complex & delicate. CRTs are
simple & have a long history of improvements.
If you make a CRT to last an average of 10 yrs many
will have to last 20yrs and more to accomplish it.
When a set got replaced it was usually 8 yrs old
& still had a good jug, it got patched up & put
in another room. When it crapped out again it ofter
went into the cellar or garage.
So the TV sees 8 yrs hard use, 5 yrs low use then
sits for years idle. Some do hard time. I had a
top-o-line M-line Zenith 19" about 1981. I sold it a
few yrs later. He ran it til mid 90's & gave it away.
Abt 3 yrs ago it got junked still working fine. I know
it isnt a rare thing............
73 Zeno
