In "The Empire Strikes Back", there is a little incident where C3PO got too nosy and discovered Stormtroopers and got blasted and head got blown off.
Later Chewbacca found it and brought it back to his cell and started repairs. If you were a Stormtrooper, would you have allowed this? Who knows, a weapon could be fabricated from C3PO's parts? So why was this allowed?
The side story indicated that Darth Vader found C3PO first and got nostalgic and eventually even gave permission for Chewbacca to bring it back to his cell to repair it without Han Solo and Chewbacca being aware of it. Darth Vader wanted his childhood friend repaired.
How about that?
