Another famous example of losing the manufacturing process and tools is FOGBANK -- a classified component used in nuclear weapons: From https://en.wikipedia.or

Another famous example of losing the manufacturing process and tools is FOGBANK -- a classified component used in nuclear weapons: From https://en.wikipedia.org/wiki/FOGBANK https://en.wikipedia.org/wiki/FOGBANK : It was soon realized that the FOGBANK material was a potential source of problems for the program, as few records of its manufacturing process had been retained when it was originally manufactured in the 1980s, and nearly all staff members who had expertise in its production had either retired or left the agency.