I am thinking that this might just be humbug. Possibly motivational humbug, however.
But I did witness first hand some shenanigans done by the Field Engineers on XDS tape drives in the 1970s. They did use a kind of resonant thing to test the limits of how well a particular tape drive was working. It would do a lot of rewinding, stopping, reversing and the like. These drives had long vacuum (work with me here) chambers, one on each side where a loop of tape would be suspended. Thus, a fast back-and-forth operation could be performed on a short section of the tape without moving the reel. The goal was to try to get the tape moving in such a way that it would pop out of the vacuum chamber and fault the tape drive.
Somewhat like the Black Team's efforts are alleged to do, the net result was that all the tape drives, after adjustment, were able to pass this tough diagnostic.
But I did witness first hand some shenanigans done by the Field Engineers on XDS tape drives in the 1970s. They did use a kind of resonant thing to test the limits of how well a particular tape drive was working. It would do a lot of rewinding, stopping, reversing and the like. These drives had long vacuum (work with me here) chambers, one on each side where a loop of tape would be suspended. Thus, a fast back-and-forth operation could be performed on a short section of the tape without moving the reel. The goal was to try to get the tape moving in such a way that it would pop out of the vacuum chamber and fault the tape drive.
Somewhat like the Black Team's efforts are alleged to do, the net result was that all the tape drives, after adjustment, were able to pass this tough diagnostic.