It is not easy to replicate the older technology. These are complicated machines, with thousand of parts, and not all of the knowledge to build them was written down. The same issue happened with the Apollo program. In the 1980s NASA started wondering what it would take to restart building Apollo rockets if they wanted to get back to the moon. After research, the answer was that even though they saved all of the engineering drawings, so much knowledge is just in people’s heads that once the Apollo generation retired, it would be easier to just start over.
No problem with 3d printing