HP Deskjet 6620 Color Inkjet Printer - Manual (Page 101)

Note: After you insert the print cartridge, verify that the copper contacts of
the print cartridge touch the back of the print cartridge cradle.
8. Push down on the print cartridge latch until it snaps closed.
9. Close the printer cover.
The printer automatically prints a calibration page.
For information about storing print cartridges, see the print cartridge storage page.
For information about recycling empty print cartridges, see the print cartridge
recovery page.
Warning: Keep both new and used print cartridges out of the reach of
children.
HP Deskjet 6600 series printer User's Guide
101