A single dust particle is larger than the gap between a hard drive's read head and its platter. That is why drives are only ever opened under filtered laminar airflow.
Step 1: Diagnosis without opening
We first check the circuit board, firmware and power. Many "dead" drives never need opening.
Step 2: Donor matching
If the heads have failed we match a donor from stock with the same model, firmware family and head map.
Step 3: Head swap
Under the laminar hood the original heads are parked and swapped for the donor set.
Step 4: Imaging, sector by sector
A hardware imager reads the drive gently, skipping damaged areas first and returning to them later. The original is never worked on directly.
Step 5: You verify
You receive a file list. Only once you confirm the files you need are there do you pay.