Complex sentence: This might break the heads free for long enough to spin up the drive and recover the data from it without powering it down once started; it would continue to run indefinitely, but might not start again if powered down.
Split into simpler sentences: This might break the heads free for long enough to spin up the drive and recover the data from it without powering it down. Once started, it would continue to run indefinitely, but might not start again if powered down.