I have an update on this disk. Well yesterday I did a "clean all" (I replaced this OS disk with a C300 woot), of course, then had to re-do the disk alignment (MBR), active it, partition etc etc. Well in the end when it's clean and usable again I did "chkdsk D: /f /r". To my surprise it didn't report any black blocks or errors and the usable space is the same as before the clean.
Is it possible the cleanall healed it? I posted a selling ad for this disk saying it had bad sectors, so do I go back and correct it to say something like "doesn't have bad sectors anymore lol"? What's the explanation for this?