Apple Macintosh PowerBook 1400 - Manual (Page 169)

13 Replace the speaker grill by lowering it into the opening above the top row of keys. Slide
the grill to the right to secure it.
Position it so that the three downward-pointing tabs are at the right front of
the grill. The tabs click into place when you slide the grill to the right.
14 Replace the battery and reconnect the plugs, cables, and power adapter.
Now you’re ready to use the expanded RAM in your PowerBook.
Lower the speaker grill,
then slide it to the right.
169 Installing Expansion Cards