Step 1
With the U-shaped clip in place, use a plastic tool to tuck the rubber plunger under the black circular opening. See Figure 1.
Figure 1 Plunger and clip
Step 2
Insert the top clip so that the side pins face downward. See Figure 2.
Figure 2 Pins
Step 3
Slide the top clip forward so that its slotted end is caught beneath the black hook on top of the keyswitch location.
Step 4
Press the top clip down carefully, taking care not to pop out the plunger.
Step 5
Bow out the "arms" of the U-shaped clip to lock the pins inside the U-shaped clip. The locked clips should lie flat.
Spacebar Replacement
Follow these steps to replace the spacebar. See Figure 3.
Step 1
Make sure the plunger mechanism is reassembled per the keycaps instructions.
Step 2
Secure the ends of the keycap's metal bar to the hooks on the keyswitch location.
Step 3
Align the keycap over the locked clips and press down.
Figure 3 Spacebar replacement