It is well known that paper and electrolytic capacitors in older electronics dry out
over time and need to be replaced. This really isn't optional. If these capacitors
don't leak or aren't shorted now, sometime, probably in the near future, they will
leak or short. We replaced every paper and electrolytic capacitor in this receiver
out of hand.
Fortunately, the same problem isn't as prevalent in ceramic disk and mica
capacitors. Troubleshooting and alignment normally pinpoint any of these that
need to be replaced.
What is not as widely known is that resistors tend to rise in value over time.
Whether a resistor will move out of spec over the years depends upon whether it is,
due to the nature of its original manufacturing, susceptible to moisture absorption.
With this in mind we always make sure that the resistors are within specifications.
Click the "list of HRO-60 capacitors and appropriate replacements" link at the left
for a handy list of the HRO-60 capacitors that will need replaced in any restoration.
We ended up replacing 25 capacitors (all but one were paper or electrolytice) and 29
out of tolerance resistors. This was in additiona to 5 vacuum tubes, 2 toggle
switches, one potentiometer and 3 lamps.