A dog knocked a MacBook off its owner’s lap onto carpet. It carried on working, so she carried on using it. A few hours later it froze, and on restart came the flashing question mark and a sound no Mac should make.
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The laptop had been in use at the time — on a lap, lid open, drive spinning. It fell a short distance onto carpet, which sounds survivable and often is. It kept working for the rest of the evening. Then it froze.
On restart it showed the flashing question-mark folder, which is the Mac reporting that it cannot find a system to boot from. And from inside came clicking. On it were photographs, documents and work files, with no current backup.
Solid-state storage has no moving parts and cannot make that noise. Any Mac producing it has a mechanical hard drive inside, which places the machine in a particular era — before Apple moved wholesale to flash.
A flashing question mark on its own can be entirely logical: a corrupt system, a lost partition, a blessed volume that no longer exists. Add clicking and the diagnosis is physical, because that sound is the head assembly repeatedly failing to find its reference position and being reset to the stop.
Parked on their ramp with the drive powered down, heads tolerate real shock — hundreds of g. Spinning, they fly a few nanometres above a surface turning at 5,400 rpm, and the tolerable figure collapses by an order of magnitude.
It absorbs some energy, and the deceleration experienced inside the drive is still abrupt. Short falls onto soft floors damage running drives regularly.
The scale is the part worth internalising. A modern head flies at something on the order of three to five nanometres above the platter — smaller than a virus particle, and a fraction of the diameter of the smoke particles in ordinary room air. There is no room in that gap for the surface to move.
Worth addressing, because people reasonably assume a Mac is protected against exactly this.
Macs of this era carried a Sudden Motion Sensor: an accelerometer that detects the characteristic signature of freefall — all three axes reading near zero simultaneously — and instructs the drive to retract its heads before impact. It is genuinely good engineering and it prevents a great deal of damage.
What it cannot do falls into three cases. A short fall gives it very little to work with: the sensor must detect the condition, signal the drive, and the drive must complete the retraction, and a knock off a lap is over in a fraction of a second. A drive part-way through a write cannot park instantly without abandoning the operation. And the sensor protects against the fall, not against what follows — heads parked correctly still have to come back out and fly over whatever the impact disturbed.
So a dropped Mac that seems fine has frequently been genuinely protected. It is not a guarantee, and it is not a reason to skip the backup.
The laptop worked normally after the fall, so it stayed in use. That is the natural response, and it is what turned a contained problem into a serious one.
Impact damage often does not present immediately. A head can be knocked out of alignment, or its suspension bent slightly, without failing outright — the drive keeps reading, marginally worse than before, with the error correction absorbing the difference invisibly.
What follows is a feedback loop, and it is the reason the delay costs so much. A head flying at the wrong height makes intermittent contact with the surface. Each contact liberates particles. Those particles circulate in the sealed chamber and cause further contact, on that head and on others. The drive has a recirculating filter designed to catch exactly this, but it is sized for the trickle a healthy drive produces over years, not for the output of a head that is touching down.
So the damage compounds over hours of ordinary use until the drive stops — and the scoring it leaves behind is permanent, on a surface where the data cannot be read back by any other means.
The rule is uncomfortable but simple: if a running machine takes a knock, back it up immediately. Not tomorrow, not when something goes wrong. A drive behaving normally after an impact is not evidence that it survived; it is a window that may already be closing.
The drive was removed and opened under filtered air. The head assembly was damaged and the platters showed light scoring in places — consistent with intermittent contact over several hours rather than one catastrophic strike, exactly as the history suggested.
A donor head-stack assembly was fitted, matched on drive family, head count and firmware revision, and the internal recirculating filter replaced to capture the debris already circulating. Fitting new heads into a chamber still full of particles from the old ones is a reliable way to destroy the new set within minutes.
Imaging then ran read-only in short controlled passes, working per head rather than straight through the address space. Logical addresses are interleaved across surfaces, so a sequential read constantly switches between a good head and a compromised one; addressing each head separately allows the healthy surfaces to be secured at full speed first, and the damaged ones approached carefully afterwards.
The scored bands were mapped and deliberately deferred, with user directories prioritised ahead of everything else. Repeatedly attacking a scored region generates more debris and can cost you the surfaces that were still good.
Everything the client asked for, returned on fresh media. The scoring was light enough and localised enough that nothing she needed fell inside it — a better result than this case deserved, and one that would have been markedly less likely after another day of use.
Recovery of a dropped drive is from £300 +VAT after a free 48-hour diagnostic, with a 50% deposit where clean-air work and donor parts are required.
Drop the drive at our Oxford Street reception, or post it to us — it costs nothing to find out what happened. You get a written figure from the fixed bands before any work begins.