Every restorer needs a reference. While modern software (like PlexUtilities or Amarra with test tones) is good, it cannot test the physical servo mechanics of a spinning disc. The YEDS18 exclusive remains the only physical standard that forces the laser to hunt, focus, and track at the absolute limit of the Red Book spec.
Because the disc pushes the tracking servos to 100µm eccentricity, a cheap plastic gear or a dry spindle motor is forced to work violently back and forth. If your player has a failing motor, the YEDS18 will finish it off in 30 seconds. sony yeds18 test disc exclusive
Today, it floats in the limbo between trash (to a streamer) and treasure (to a restorer). If you ever find one at a garage sale or a flea market, buy it. Do not hesitate. Pay the $5 or $500. It is worth it. Every restorer needs a reference