A WD My Passport 4TB that was dropped, now ticks and is not recognised. The owner opened it and watched what happens: the head starts in position, sweeps out across the disk, then flicks back. Repeatedly. That is an unusually precise observation and it names the fault exactly. The head is looking for the servo pattern written on the platter, which is what tells it where it is. It cannot read it, so it fails to settle, retracts to the ramp, and tries again — and the tick is the retraction. There are two things to do with that information. The first is to stop, because every sweep is a damaged head passing over the surface holding the data. The second is to acknowledge that the drive is now open, which adds a contamination problem on top of the head fault.
| Media | WD My Passport 4TB, dropped. Ticking, not recognised. Opened by the owner, who observed the head sweeping across the platter and retracting repeatedly. |
| Reported situation | WD My Passport 4TB · dropped · not recognised · ticking · opened, head seen to sweep over the disk and flick back · recovery sought. |
| Fault class | Head fault caused by impact. The head cannot read the servo pattern, so it sweeps, fails to settle and retracts, producing the tick. The platter data is normally intact and is reached with matched donor heads under laminar flow. Repeated power-ups are the hazard, and the earlier opening means contamination must be assessed. |
| Equipment used | Not run further given the fall and the observed head behaviour · put on a bench supply with the current limited and profiled, the sweep-and-retract pattern characterised · opened under laminar flow, contamination from the earlier opening inspected and cleaned, head stack and platter surfaces examined under the microscope at magnification, a matched donor head stack installed and the alignment set · imaged on DeepSpar with PC-3000 UDMA driving the drive, data located and validated in R-Studio. |
The servo pattern is worth explaining because everything here depends on it. When a platter is manufactured, a precise positional pattern is written onto it — wedges of information spaced around every track saying exactly where the head is. Without reading that pattern the head has no idea of its position and cannot settle onto a track. Every read the drive ever does begins with finding it.
So a head that sweeps out, fails, and snaps back is a head that cannot read the servo. After a fall the reasons are the usual ones: the head is damaged, the slider is chipped, or debris from the impact is in the way. The firmware responds by retracting and retrying, which is the tick, and it will do that indefinitely because it has no better plan.
The observation is genuinely useful and the way it was obtained is not. Opening a drive to watch the heads means unfiltered room air over the platters, and particles that are enormous at the flying height involved. That does not necessarily ruin the recovery, but it adds a step — inspection under magnification and a clean — and it adds uncertainty that was not there before.
The work itself is a head replacement with matched donors under laminar flow, and the outcome depends on the platters. A 4TB portable drive of this generation is a shingled, high-density mechanism with very fine tolerances, which makes it less forgiving of both contamination and repeated sweeps than an older drive would be. All the more reason it should have been switched off at the first tick.
It was not run further, since the fall, the tick and the observed sweep-and-retract left nothing to establish by powering it. It was run from a bench supply with the current limited, where the pattern was characterised in a few seconds. It was then opened under laminar flow, and the first job was inspecting the platters under the microscope at magnification for what had settled during the earlier opening, and cleaning it. The heads had failed. A matched donor head stack was fitted and the alignment set afterwards, and the drive imaged on DeepSpar with PC-3000 UDMA driving it. The filesystem was reassembled in R-Studio off the image and the contents opened and checked before anything went to fresh media.
Heads replaced under laminar flow, contamination from the earlier opening cleaned, the drive imaged and the data brought back onto fresh media. Assessment free, and one fixed written figure with VAT in it before the work started, with half due before the clean-air stage and the balance owed only on the result. Two honest notes went with it. The owner's description was accurate and saved diagnostic time. And the opening added risk that was avoidable — everything worth knowing was already established by the tick and the fall, and the lid did not need to come off to confirm it.
Switch it off and do not open it. If it has already been opened, put the cover back on to keep further dust out and say so clearly when you send it, because it changes how the job is approached and what is realistic. A tick after a fall is all the diagnosis anybody needs — the head cannot read the servo pattern and is retrying, and each retry passes a damaged head over the surface your files are on. Watching it happen does not add anything except contamination. Do not spin the platters by hand, do not touch anything inside, and do not attempt to swap heads yourself using a video as a guide. Box it, note how many times it has been powered since the fall, and send it tracked.
Each file below comes from a genuine enquiry taken from households and firms across Aberdeen, Aberdeenshire and the wider north-east, anonymised so nobody can be identified. Each one sets out how the fault was reasoned through, what was done about it, and which equipment did the work.
A shop that says a part inside is broken has read a dropped drive correctly — that part is the head assembly, and it is changed in clean air
A socket that has been strained once and then yanked has failed at the connection, and the drive is read past it rather than through it
A drive that tries to start and gets no further has failed at the heads — the light and the noise are the last two things it can still do
Assessment is free and takes 2 working days at most once it lands, the figure is fixed in writing, and logical work carries no fix no fee. Begin online, or lift the phone.