Those of us who have recorded video and audio on magnetic tape have by now learned an essential truth: magnetic media does not last forever.
Like all known storage media, tape is not permanent. Sadly, no one knows exactly how long the recorded content will play on old tapes. This is all trial-and-error stuff.
After Orson Welles died in 1985, I was offered a collection of his old tape and disc recordings of the Mercury Theatre radio shows from the 1930s through the 50s to edit and enhance for a retrospective called “Theatre of the Imagination.” I did the project, but had no idea what I was getting into.