Data Recovery Case File · Second Fixes & Trade Handoffs · A Number That Predicts the Outcome
One Failed Head Means One Pair of Surfaces Is Unreadable and the Others Are Not
This enquiry arrives with a diagnosis specific enough to reason from. A portable drive of around 1TB where the reported cause is failure of head number one, with a head replacement and a working copy identified as the required procedure, and a request covering transfer to new media and courier handling. Knowing which head failed is more useful than knowing that one did, because it predicts how the content is distributed against the damage.
| Media | 1TB portable hard drive with a single head reported failed by a prior assessment — remaining heads not implicated; head replacement and imaging to a working copy identified as required |
| Reported situation | Portable drive holding approximately 1TB · prior assessment attributing the fault to failure of one specific head · head replacement identified as the required procedure · transfer of recovered content to replacement media requested · collection and return by courier requested · quotation sought covering all elements |
| Fault class | Single head failure on a multi-head assembly — surfaces served by the affected head unreadable pending replacement; remaining surfaces readable and content distributed across all of them |
| Equipment used | Head number treated as predictive of recoverable proportion rather than as a label · laminar flow bench inspection with the affected surfaces assessed for contact damage before any rotation · matched donor assembly fitted with the full stack replaced rather than a single element · imaging under capped timeouts in supervised sessions · content delivered to supplied replacement media |
The decode: what a head number tells you, and what the procedure involves
How a drive of this size is arranged: one or two platters with a head above and below each surface. A 1TB portable typically carries two or four heads on a single moving assembly, numbered by position.
Why the number is informative: each head serves one surface. Knowing which one failed identifies which surface is currently unreadable, and by extension how much of the drive is affected.
Why that does not mean a corresponding fraction of files is lost: content is not stored surface by surface. Drives write across all surfaces at each cylinder position before moving inward, so a single file is spread over every surface rather than confined to one.
What that means in practice, and it is the important part: a drive with one failed head returns almost nothing usable until the head is replaced. Every file is missing the portions that lived on the affected surface, which is why partial reading of the working surfaces is not a shortcut.
Why replacement is therefore the whole job rather than an option: the objective is to read all surfaces. Nothing useful is obtained by reading three of four, and that is why the prior assessment identified the procedure it did.
Why the whole assembly is replaced rather than one head: the heads sit on a single moving arm and are aligned to each other. Individual heads are not separable in practice, so a matched donor assembly is fitted entire.
What determines whether it works: the condition of the surfaces the failed head was serving. A head that stopped reading without touching the surface leaves it intact; one that made contact scores it, and the new heads will read a damaged surface no better.
Why that is inspected before anything is committed: it is the difference between a routine recovery and a partial one. Surfaces are assessed under filtered air before rotation is attempted.
Why a working copy is specified in the procedure: a drive with replacement heads has a limited working life. The whole surface is imaged in supervised sessions and every subsequent operation runs against the copy, rather than repeatedly returning to a rebuilt drive.
Why quoting all the elements together was sensible of him: transfer media and carriage are real costs that surface late otherwise. Asking for them in the same figure avoids the common experience of a quotation that grows.
On the bench
The head number was treated as predictive of recoverable proportion rather than as a label — each head serving one surface, while content is written across all surfaces at each cylinder position before advancing, so a single file spans every surface and one failed head leaves every file incomplete. Replacement is therefore required rather than optional, and heads being aligned on a single moving assembly are fitted as a matched set. Surfaces were assessed under the laminar flow bench before any rotation.
The outcome
The head number treated as predictive, the affected surfaces assessed before any rotation, and a matched donor assembly fitted with imaging to a working copy. Free assessment, one fixed written figure including VAT covering media and carriage, 50% of parts and labour upfront with the balance only on successful recovery. The decode: knowing which head failed predicts the shape of the outcome. Content is written across all surfaces at once, so one failed head leaves every file incomplete — which is why replacement is the job rather than an option.
When you are told a specific head has failed
Ask two follow-up questions. First, whether the affected surfaces show contact damage, since a head that stopped reading without touching the surface leaves it intact while one that made contact scores it — and new heads read a damaged surface no better. Second, whether the quotation includes replacement media and carriage, as you have, because those surface late otherwise. Understand why replacement isn't optional: content is written across all surfaces at each position, so one failed head leaves every file incomplete rather than losing a quarter of them.
Ask about the surfaces — call Manchester Data Recovery on 0161 871 0788; head number treated as predictive, surfaces assessed under filtered air before rotation, matched donor assembly fitted with imaging to a working copy.
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Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.