There are two occasions when you need to replace an ink cartridge.
The ink cartridge is very low and you want to replace it with a full cartridge for unattended printing (you can use up the remaining ink in the first cartridge at a more convenient time).
The ink cartridge is empty or faulty, and you must replace it to continue printing.
Do not try to remove an ink cartridge while printing.
Remove an ink cartridge only if you are ready to insert another one.
When a cartridge runs out of ink, the current job is cancelled.