Dell Precision WorkStation 420 Service Manual page 26

4. Lift the bottom of the cover, allowing it to pivot up toward you.
5. Disengage the tabs that secure the cover to the top of the chassis, and lift the cover away.
Figure 3. Computer Cover Replacement
To replace the computer cover, perform the following steps:
1. Check all cable connections, especially those that might have come loose during your work. Fold cables out of the way so that they do not
catch on the computer cover. Make sure cables are not routed over the drive cage—they will prevent the cover from closing properly.
2. Check to see that no tools or extra parts (including screws) are left inside the computer chassis.
3. Face the left side of the computer and hold the cover at a slight angle as shown in Figure 3.
4. Align the top of the cover with the top of the chassis and insert the three hooks on the cover into the three recessed slots on the computer
chassis so that the tabs catch the hooks inside the slots.
5. Pivot the cover down toward the bottom of the chassis and into position. Make sure that the securing hooks at the bottom of the cover click
into place.
1 Release button
1 Hook (3)
2 Recessed slot (3)