The static crackled through the speakers at Record Revival's flagship Nashville store as another customer returned a "mint condition" 1977 Fleetwood Mac album—the twelfth return that week for the same issue. Surface noise. Grading inconsistencies. Mislabeled pressings. The vintage vinyl chain's $42M business was bleeding from a problem no human grader could solve: authenticating 50 years of music history buried in grooves thinner than a human hair.