Piru,
My 20 years with CBM gear had some bearing on the answer. Although technically correct that the factory prep would have mapped out(surface)defects,and written the bad block list, there are factors that create bad data blocks, and factors that will create NEW surface blemishes that can be mapped out.
The solution, as suggested by AmigaKit, was to run QuarterBackTools (I prefer AmigaBackTools, but have both). These can correct bad data, thus repairing the data block. Neither program repairs original mapped out blocks. Then run the program I suggested, to map out the blocks. The drive should be replaced, but could be used during that phase.
As a side-bar: I have 2 Fujitsu SCSI drives, with 7+ years of service non-stop, never powered down except to clean the drive cage, and correct bad data. That is 500,000 hours without mechanical breakdown. I am about to turn them back ON next month. (I did a test last month, and it's 100%).
