I don't think this kind of thing is all that uncommon for military airplanes that have been long out of production. I recall reading a decade or two ago that our local air guard wing had to fabricate some of its own replacement parts for its F-16s (IIRC, then some of oldest that were still in service).

I also recall that Lockheed had to take special effort to preserve production know-how and tooling for the F-22 when they shutdown production early, so it would be possible to restart if needed. You can't capture everything you need to know in blueprints and documentation.