Canon PIXMA MX860 series Getting Started page 9

Tilt the Print Head forward and set it in place.
~-----------------------
• Do not knock the Print Head against the sides of the holder.
• Install in a well-lit environment.
Lower the Print Head Lock Lever (F) completely.
~----------
• Pinch the Print Head Lock Lever firmly and lower it
gently.
• Once you have installed the Print Head, do not remove
it unnecessarily.