Dell Dimension 4400 - Manual (Page 8)

Reattaching the Hinge Arms
1. Shut down the computer .
2. Disconnect the power cable from your computer.
3. Remove the front door, if it is attached.
The front door snaps off of the two hinge arms.
4. Remove the front-panel insert above the front-door bay area.
Pull the bottom of the insert with your fingers to remove it.
5. Lift both hinge arms to the horizontal position.
6. Use the two view slots to align the pivot bar with the two pivot-bar slots.