Damage of heads, manifested by knocking and not running hard drive is typical. The heads should be replaced with efficient one and data should be copied. Data recovery becomes complicated when the heads are physically damaged.

The heads float above the plates on a air-cushion generated by high speed of the plates. Any disruption in this state leads to damage of the heads and / or the plate. Shock or fall of working hard drive may cause a collision between head and a plate, which can result in a variety of ways:

• impact force is so small that will not result in immediate damage, heads will degrade over time, the surface of the plate at the point of impact will be impossible to read (symptoms of bad sectors);
• the impact will be so strong that tear off parts of the plates surface will leave a cavity on the surface of that plate. The data from this section will obviously be unreadable and head displacing over this part of the surface will be damaged over time, often violently;
• head will be damaged immediately upon hitting in the plate. Often distracted from the pressure. The pressure of the head without MR element (reading/writing element) will be scratching the plate, causing irreversible damage of the surface which often makes data impossible to recover;
• head will be damaged at the time of leaving the plate, tearing off the arm, often blocked at the parking or between the parking area and a plate. This case is often beneficial to the data because the blocked head will not turn back on the plate and you will not be able to scratch it.

Damages not causing snapping off the heads usually is not danger to the data. Knocking hard drive after changing the head will usually allow You to copy data. Running the knocking hard drive may cause tearing off the head which may press the surface of the plate, which will lead to the irreversible destruction of that surface. Some hard drives with ragged or damaged head will not move it out of it on the plate, and some HD's without self-diagnosis will put the pressure on the plate by itself, causing scratches of the surface.

At the picture at the top You can see the hard drive 00D7B0 WD10EAVS with heads tear off after the fall. Head 1 (indicated by the lower arrow) and head 3 (indicated by the upper arrow) are damaged, but the head number 3 has caused serious damage to the surface. Pressure of the head, probably cambered by a parking, was scratching the plate. Unfortunately, the damage of the heads did not stop them from putting on a plate.

At the upper band photos are HDS721010CLA332 Hitachi hard drive heads. Snapped off sliders and sharp fragments of their attachment to heads arm caused damage of the plates surface.

In the lower images You can see ST9160310AS hard drive head. After opening the hard drive heads were stuck between the parking and a plate. Traces of reflected head on the surface 1 is visible, head 0 is tear off. To remove the damaged heads from parking and the plate, without putting them on a plate, somebody bent the head with parking.

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