Okay. Allow me to explain what happen to the motor , and then the alignment issue. The motor is the component that the platters sit on nicely and turns them at a specified rpm. Inside the engine, we find motor bearings. These bearings help the engine turn smoothly without a vibration. Storage Review has a fantastic reference manual related to the intricacies of disc drives. You need to read it if you would like to understand more.
Hard drives with multiple platter disks
Now, when the best external hard drive is dropped, and the engine doesn’t spin, the bearings probably are dislodged from their grooves and clog the distance the engine needs to spin. Oftentimes, the motor becomes rigid that no torque force applied will do some good. In some cases, the engine is less rigid, but won’t turn freely. In either scenario, it doesn’t look good.
About alignment: When the engine cease or become stiff after the drop, particularly when the hard disk was running, the disk platters may change. The abrupt stop of this platters may shift them slightly off the engine. Hard drives with multiple platter disks are aligned at any time before shipment. For example, when a drive reads monitor 0, it reads track 0 to all surfaces. The tracks are adapting, and thus the sectors on the paths. So any shift, would misaligned the sectors from one platter to the next. So any shift, whatever small it is, will render the drive inoperable for information recovery. It’s safe to state that nobody can realign platters on a 3.5″ form factor drives found on desktops and externals.
Even without a disc shift, motor problems are the Achilles’ heel of data recovery. You can’t simply remove the platters and move them on another disc. Some companies have introduced some platter tools, but there is nothing out there we all know of is 100% full proof.