Go out and buy a decent Western Digital Drive to replace the faulty one your trying to fix. Most bad sectors are caused when the head wears out and makes contact with the disk surface. leaving a small piece of plastic, each time the head passes over it the lump gets bigger then it starts bouncing.
If you want to rescue whats on the drive, put it in a waterproof sealable back and stick it in a freezer overnight. Following day prepare a computer with a system drive working, then unoack your frozen one, get it in the machine and copied as quick as you can. After that bin it.
Most drives fail due to serious overheating, it warps the disks and track arms. If the drive is showing even a single error its time to buy a new one.
