wrote in message
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Why should someone replace ALL the capacitors on old Tube equipment?

It seems that some people advocate that.

I understand that the electrolytic caps contain chemicals which decay
over time, from the chemicals corroding the metal parts. So,
electrolytic caps should always be replaced. But why replace the old
paper caps coated with wax? All they are, is metal foil and paper rolled
up, and as long as the wax is sealing them to keep out moisture, why
should they become defective?

Waxed paper capacitors are notorious for moisture absorbtion and becoming
leaky.

There are plenty of other types of dry capacitors that don't last forever in
the high temperature around tubes.