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Bob, this is where I always get a little confused. If it's true that ANY tube found today that has now gone to air will "only work for 30 days or less" after rebuilding (which I have to believe, since you've been studying these things for years), that must also affirm that ANY such tube only began leaking after some finite event along its lifetime (failed weld, failed glass to metal bond, stress crack in the glass, etc.). For whatever reason, I can't get it out of my head that at least SOME of the tubes found today that have gone to air did so at an even rate from the very moment they were made, and only at some point along their lifetime (twenty years ago, two years ago, or two minutes ago) enough air entered to finally consume all of the getter material and cause the filament to fail. If it took ten or twenty years for that to happen, then why couldn't it be assumed (unless the leak were made worse during the rebuilding process) that the rebuild would not last equally long? Not doubting you here - just wanting to understand why that's not possible or even likely for some tubes.
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