[morzh]

John

ripple rating is very much corelates with ESR (this will dictate the heat losses) and the size/temperature rating (this will dictate the heat transfer frm the cap to the ambient, and the resistance to heat damage). The old caps were large, so the cooling was not an issue.
I simply do not know their ESR or Ripple ratings as they were never published, or if they were - they are nowhere to be found.
But...them drying up withing 10 years or under (the repairs were often made in late 30-s - early 40s to replace the electrolytics) tells me that it was either the bad sealing and therefore evaporation of the liquid, or the same exacerbated by heating of the cap that would speed up the evaporation and drying up.
However I often find the same caps (like these two I just gutted) that are not dry and exhibit the capacitance in excess of the specified originally, which tells me they did not heat up much and maybe simple developed leakage. Which might be the result of not being subjected to high ripple.
So maybe their ripple rating was not that good after all, and it was just the question of the type of the circuitry they were working for: how much consumption, and therefore ripple current the cap experienced.

But it is all guesses by now: I doubt anyone ever did the measurements, or if someone did, that the records were kept.

Yes, even for me it is probably lifetime
Hey.....there's that silver lining!