Hello James,
vacuum tubes are nothing else than modified light bulbs so the manufacturing is related and the "Pumping Mills" of the light bulb was incorporated into the commercial tube production.
All radio tubes were made with those sealing machines and only some specialty tubes were made on "Straight Pumping Stands".
Most of the machinery in the Chinese factory is old Philips/GEC origin, but most of their Getter Mills are state of the art, diffusion pumps on every position with a mechanical roughening pump. Theoretical they should be able to make tubes that are out of this world, but there is no improvement in "Made in China" tubes over the last 10 years or so.
Even Telefunken never had those very high vacuum machines (their mills used rotary pumps) their tubes were still light years better, even today nearly 30 years after they stopped production!
The over all impression of the plant in China is a kind of dirty and to quotes of former Telefunken workers the production floor was cleaner than a surgery room in a hospital.
Most high volume tubes like the EL84 were automatically assembled but specialty tubes like AC701 were 100% handmade.
Thanks for sharing your experience of "Glass Working", if you have more info and pics, that would be highly appreciated.
All of the in-production tubes have big problems with stressed glass that was not properly tempered or sealed. Aside the glass and the raw material issues with in production tubes, the filament bears the biggest challenge to make those tubes usable in studio application. Most east european tubes have issues with magnesia vapor after a 500h lifetime.
With your knowledge in bulb manufacturing I guess you understand the difficulty of making double helix filaments, another staple of most Telefunken tubes, there is no in production tube that has that standard feature of most NOS western type tubes.
Best regards,