I’m willing to bet there were far more failed tubes in the early years then most here would like to admit. just the sheer amount made would dictate to a much larger failure rate then we see today. there was also budget cheep tubes made back then so its all relevant. The good tubes made in the past are now stupid money.
new production tube have also come a long way in the past decade to the point i think they are on par with or close to the average NOS stuff. lets face it the really good NOS tubes are getting long in the tooth for availability so there are only the mediocre NOS tube really available in any quantity.
I’m just happy someone is trying to make new tubes still and good quality ones at that.