The initial diagnosis determines the failure mode of the drive, failure modes can be;

Logical, for example where a drive is working, but the data is no longer accessible.

Electronic failure where one or more comonents have failed on the electronics board on the underside of the drive, or internal head pre-amplifier circuitry has failed. Both require temporary repairs made so your data can be accessed.

Mechanical failure, for example the motor has failed or the hard disk's heads are clicking.

Following the diagnosis, any necessary repairs are made, if the drive needs to be opened in order to facilitate such repairs, the work done in a Class-100 clean air environment to avoid particle contamination. Once the repairs are complete and the drive is deemed recoverable, an exact copy (or clone) of the data is made to a second suitably sized media.

Finally, the data on the image media is tested for accessibility and that the critical files open within their respective programs, any further logical repairs are made if necessary. Once testing is complete, the recovered data is then copied to CD or DVD - other recovery media options are available at cost.