In the event that you lose your original UNDO.BIN file, please do not be tempted to apply a foreign UNDO.BIN. The solution is to hack your drive again, but this time by using a HDDSS.BIN file that has been modified to reflect your original WD drive's own parameters. In other words, instead of hacking a WD drive to look like a Fujitsu or Hitachi, you will be hacking a WD drive to look like a WD drive.HDDHackr - lost UNDO.BIN - how to restore capacity:www dot hddoracle dot com/viewtopic dot php?t=141The following article explains what HddHackr does and how it does it.HddHackr — how it modifies a Western Digital drive for use in an Xbox 360:www dot users dot on dot net/~fzabkar/HDD/HddHackr_analysis.htmlThe author ("aimtrading") has posted the full source code here:forum dot hddguru dot com/viewtopic dot php?f=13&t=26971