Canon PIXM MX300 Series User Manual page 130

Caution
Be sure to hold the Scanning Unit (Printer Cover) firmly, and be careful not
to get your fingers caught.
Note
If the error message is still displayed after the Scanning Unit (Printer
Cover) is closed, see
When you start printing after replacing the FINE Cartridge, Print Head
Cleaning is performed automatically. Do not perform any other
operations until Print Head Cleaning finishes.
If the straight line is misaligned or the Print Head position is
misaligned, align the Print Head position.
See Aligning Print Head on the
An Error Message Is Displayed on the
Machine.
130
LCD.