As i know, 'phsically' bad sector has no way to recover even we used some diagnostic tools given by the manufacturer. we can try to retrieve some data that dropped on phsical bad sector but not all the data we can trace them back. i used NDD and PCtools before and they worked fine. but there is no PCtools anymore in the market. Some area that shown as bad sector may be not really bad but only go weak. we can call it 'weak sector'. Some of the protection diskette and keydisk use this method to avoid the floppy to be 'diskcopy'. When we want to diskcopy a keydisk, computer will copy those weak sector as bad sector and the copy process will ignore some data that saved in weak sector. This will make the duplicated copy won't function correctly. Some of the copy tools will transfer those data that dropped on weak sector to different area that is good, this also will cause that keydisk become malfunction. 'Logical' bad sector may cause by viruses or some software. This is not really bad sector. Those bad sector will become good sector if we format that media (HDD/FDD). Tools like NDD can recover Logical bad sector or even changes those good sector into bad. SO 'BAD SECTOR' can be happened in HDD and FDD. I agree what as MX said, it is good idea to send bad sector item for RAM or change that media with good one to avoid data lost.