[Username1]

Many of the older original parts were subject to decaying because of materials
used, drying in the case of capacitors, heat damage and drifting values in
the case of resistors, and insulator break down for coils, dielectric material
that did not stand up to the voltages used.... In a lot of cases also once
a minor part went bad, it could cause over current conditions to burn out
transformers, that are not available to replace at any price....

Replacing a lot of those parts is just buying insurance. Insurance that the
older part might be ready to go- and that the new part chosen may be
of at least good enough quality that for the immediate future, the chance
of failure, and taking out a more expensive, and hard to find part may
not happen..... Like a flyback, yoke, etc....

There is also the argument to be made that the set will work better if
all the parts are brought back to their designed values. Tolerances of
some non critical parts were often specified to be 20%, quite a bit off
designed value..... And over time they drifted even more..... Doing so
for every part means you have to re-align all the circuits to achieve
the goal of a better working set... There are a few people here that have
done all the work required, and have been rewarded with a set that can
be run for hours at a time, and years of use without having to fiddle
with all the knobs with each use, and rolling picture after a few hours,
and constant retuning over the hours of use.... But really good parts
have to be used..... Any you have to be careful, or you end up with
more trouble than if you just fixed the original problem and used it on the
old parts.....



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