The broken device is a quest item used in the Mourning's End Part I quest. It is given to the player by the Head Mourner in West Ardougne and the player must have it repaired by a gnome who is being held captive by the mourners. The gnome will repair the device, turning it into a fixed device, but only after the player has tickled his feet with feathers and given him some toad crunchies.
The broken device can be re-obtained from the chest in the Head Mourner's office. To get it fixed, you will need a Tarnished key, a piece of Leather, a Magic log and some Toad crunchies. The gnome will still repair it after Mourning's End Part I is complete.