How to Repair Hard Disk Drive
There are different kind of hard disk problems you may experience. First, it Hard Disk sentinel shows suggestions about improving the situation (for example by changing/improving the data and powercables and connections, veryffy power supply, improve cooling) it is recommended to do it prior any further steps.
Then it is important to verify if the hard disk status is stable and there are no further problems with the hard disk surface which whould need to be corrected. Please check How can I perform a deep analysis ? section for details about using the test in hard disk sentinel (PRO) software to reveal and fix hard disk problems and making the hard disk surface more stable.
If the hard disk surface test completes successfully, without reporting any errors (even if the healts is lower than 100% and bad sectors are displayed in the text description), these bad sectors are no longer used by the hard disk. Instead, a spare area is used for all reads and writes targeting those bad sectors. This means that disk surface test (even the tests in Hard Disk Sentinel) does not acces those sectors, but test the remaining data area and the spare area - this is why only "green" (perfect) blocks reported.