Standard tools attempt to remap bad sectors to the G-List (growth list). WD Marvel goes further:
Furthermore, the existence of WD Marvel highlights a fascinating subculture of digital preservation. It is a product of years of community-driven reverse engineering. Because Western Digital does not release its proprietary repair manuals or firmware schematics to the public, the developers of WD Marvel had to painstakingly map out the internal logic of different drive families (such as Zephyr, Palmer, or Spyglass). This creates a constant cat-and-mouse game between manufacturers who lock down their hardware and the data recovery community that seeks the "Right to Repair." wd marvel repair tool top