The Drive Motor could be broken but this is very unlikely as well. The most likely thing to have moved is a piece of plastic that blocks the Air In Hole on the drive to prevent any ingress of large lumps of rubbish.
As for requiring a part to open the drive this is rubbish. They use a Torx or Tamper Proof Torx Driver generally a number 10. The Tamper Proof Torx is the same as a normal Torx Driver with a hole up the center of it where a lug is in the screw to prevent placing a Torx Driver into the Head of the screw. There is a Nut as well but this can be removed with any adjustable spanner.
As for recovering Data if the Covering on the unscratched it is possible to recover the data. Even with light scratching it is possible to recover Data but if the Magnetic Material is gone then there is nothing left to recover from. If you shake the drive and it rattles like it has thousands of loose parts in it then you most likely have a Glass Platter IBM Deskstar Drive which had Glass Platters which did break when dropped. But these are old drives the new ones all have Aluminum platters in them coated with a Magnetic Material which is what actually store the data. The most likely thing to go wrong with these is that the Servo which controls the heads no longer works.
Now for the fun part if you open a HDD it should be opened in a Class 1 Clean Room so if whoever you are taking the drive to doesn't have one of these and very few places do they are not capable of recovering the data off the drive. Call up Seagate Recovery Services or On Track both of these companies can open the drive replace whatever is necessary and recover Data off the drive.
If the drive was running at the time of the fall the heads most likely came into contact with the Platters and have scratched the magnetic covering off part of the platter. When this happens it is impossible to recover data off the affected area of that platter but the remaining bits which is the majority of the platter is easy to recover the data off.
The recovery houses who routinely perform this type of work have special machines which allows them to read directly off the platter and save your data. Buy your description the places that you have taken this drive to have a piece of software and can only recover off working drives. These are not actually a Data Recovery House they are little better than places who have untrained people to read a screen and tell people what to do it make it work again so they are effectively a Help Desk who once they run into something not listed can not proceed any further.
Col
