Oki C3520 - Manual (Page 84)

Maintenance > 84
2. Press the cover release (a) and open the top cover of the
printer (b) fully.
3. Note the positions of the 4 cartridges.
WARNING!
If the printer has been powered on, the fuser may be
hot. This area is clearly labelled. Do not touch it.
a
b
1. Cyan cartridge 2. Magenta cartridge
3. Yellow cartridge 4. Black cartridge
1
2
3
4