HP MFP Analog Fax Accessory 300 Fax Manual page 26

12 Secure the tab on the left side of the fax card strap.
Securing the left side of the fax card strap tab
Figure 1-22
13 Align the formatter board in the tracks at the top and bottom, and
Aligning the formatter board
Figure 1-23
18 Chapter 1 Setting up
slide the board back into the MFP.
ENWW