Canon MultiPASS C3500 User Manual page 250

If you are using the BC-21e Color BJ Cartridge and your output is
blank, one of the BJ tanks is probably out of ink. See the instructions
starting on page 9-16 for replacing a BJ tank.
The following procedure describes how to replace the BC-21e Color
BJ Cartridge with the optional BC-20 Black BJ Cartridge. Follow the
instructions in this section to replace an old BJ cartridge or to change
BJ cartridges when you are switching between the BC-21e and any of the
optional BJ cartridges.
You only need to replace the BC-21e Color BJ Cartridge when the print
head is damaged (or after printing approximately 2000 pages). If one of
the BJ tanks (either color or black) in your BC-21e Color BJ Cartridge is
out of ink, see the next section (page 9-16) for instructions on how to
replace a BJ tank.
To replace the BJ cartridge, follow these steps:
Press the
CARTRIDGE
button.
Open the
printer cover.
9-12 Maintaining the MultiPASS C3500
The cartridge holder moves to the center
of the unit.
Grasp both sides and lift it up.
DO NOT TOUCH THE
RIBBON CABLE
DO NOT TOUCH THE
GUIDE RAIL
DO NOT TOUCH THE
ROUND SHAFT
Chapter 9