There is no exist program to repair physically damaged sectors - the so-called bad sectors.
The longer we force a disk to work, i.e. to read individual sectors, without knowing its technical condition, the more difficult data recovery may turn out to be.
Such a situation may take place when the read-writing elements of heads assembly have been damaged and the working heads is unnecessarily loaded and is further degraded, or the surface of the disk platters has been damaged, which may be further damaged during scanning.
While in the first case, the solution is to replace the heads from the donor disk, the damage to the surface of the plates is irreversible.
If the drive is still able to read data, you should immediately make a sectoral copy of the damaged disk to a healthy disk and only from it recover data.
In the event of a failure of the hard disk electronics it's replaced in modern drives is ineffective.
This is due to the fact that currently produced hard drives have such a high data density that each of them is assigned individual operating parameters stored in the ROM memory.
If we only replaced PCB the drive is not able to properly calibrate itself to work.
As the technology develops, there are also new bugs that are also confused with PCB damage and are located on the firmware side of the so-called Service Area. This, in turn, is located on the magnetic surface of the disk and has nothing to do with external electronics.
In addition producers of magnetic carriers have started to more and more secure their products by blocking service access and hardware encryption of the user's content.
Issue often confused with damage to electronics. In most cases, however, is related to damage heads assembly.
During operation, the heads are raised on an air cushion, the effect of this phenomenon is the high rotational speed of the platters, and the distance between the writing-reading element and magnetic surface is about 1 micrometer.
Heads failure may result from a power issue as well as from any shocks during operation. In such a case, the reading and writing elements may become detached and contribute to scraching of the platters surface.
The second common defect related to the shock or fall of the disk is the sticking of the reading-writing elements of the heads to the surface of the platters.
In such a situation, the disk will not be able to start the drive axle, and disturbing noises will be heard from the drive - for example a soft squeak.
It is best not to start the drives after such events or with similar symptoms.
Opening the hard disc drive under unfavorable conditions, i.e. outside the laminar chamber, is a common mistake.
And it is the erroneous claim that inside the traditional disk there is a vacuum or there is a special gas in it.
In hard drives contain high-purity air, and the drives themselves are equipped with vents and filters to equalize pressure and allow the formation of an air cushion.
Opening the cover in such conditions results in the platters become dirty, and you should remember about the aforementioned data density - a dust particle that may be invisible to the naked eye may hit the head silder and damage it or scratch the magnetic surface when the platters are rotated and damage most of the sectors.
Data recovery after such home treatments is very difficult or sometimes even impossible.
Returning for a moment to the information that hard drives contain gas - yes, helium-filled drives, the so-called Helium Hard Drive, have recently been produced and available for sale. They have two covers, the top of which is integrated with the body of hermoblock and is not removable.
This is the last thing what need to do.
There are two situations when it is necessary to disassemble the platters.
The first is when the platters motor cannot correct rotation due to damage to the bearing, winding or bent axis.
The second situation is the need to inspect the surface and remove any contamination..
Until recently, desyncing platters were thought to prevent any kind of recovery procedure.
Some drives are actually very sensitive to changing the position of the platters in relation to each other, but we managed to develop a method of marking their position and programmatic control of the read area.
Thanks to these measures, it is possible to recover data from disks that have a disturbed magnetic surface, were contaminated with dust from sawing, and those in which contamination comes from external conditions and is located on the bottom surfaces of the platters.