IBM S544-5343-03 - Manual (Page 158)

7. Loosen and remove the thumbscrews that hold the slot cover. Remove the cover
and store it for future use.
8. Insert the card into the slot, aligning it with the two guides at the top and bottom of
the slot. Slide the card vertically into these guides, pushing slowly and firmly until
you can feel the card seat into the socket.
138 Network Printer 17: User’s Guide