When is used used up?


Is there a rule of thumb that says the savings of buying used equpment is offset by the age of said equipment? Surely, aging negatively effects circuits -- welds weaken, capacitors lose capacity, transistors tire, wiring oxidizes, etc. My first amp in 2000 was a Mcintosh 250 in A- cosmetic condition. When I replaced it five years later with an HK PA2400 (used), my system took on new life (more than the increase in wattage).
Seems like when a component is old, it's old, be it sacred cow or not.
garn509
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All I can say Elizabeth, is you really seem to be in the know. Hats off to you! I learn something new here almost every day.
Liz, good thoughts on environmental factors. I did not include the question molecular decay of components and connections which is a factor of the quality of construction also. So, I guess we have -- where used, how much use, and what is it.
How's that analogy work for us humans?? Same/same I guess. I personally know I have been out in the sun,way long.