Dell Inspiron 1420 (Mid 2007) - Manual (Page 143)

Adding and Replacing Parts
143
6 Install the replacement modem by pressing the modem into the connector
on the system board.
NOTICE:
The connectors are keyed to ensure correct insertion. If you feel
resistance, check the connectors and realign the card.
7 Connect the modem cable.
8 Tighten the three screws and replace the modem cover.
1 screw 2 pull-tab
3 modem cable 4 modem
3
4
1
2