Woofrey,
You may actually find that the original cartridges supplied are not filled to the same level as the replacements - perhaps as little as 1/4 or 1/3 the normal amount. This has been a common ploy by manfrs in their efforts to keep the cost of the printer down, particularly with inkjet printers .
Not all manfrs do this, and not necessarily this printer model, but worth bearing in mind.
SD