By removing the tapered piece of plastic between the clip and the
reservoir, the ink level becomes visible when looking behind the clip,
also when the catridge is mounted in the printer.
Removing is done by bending the clip downward and then cutting just
above the bend through the mentioned plastic piece with a
knife using a sawing motion. Don't touch the clip.
A peculiar thing is that my ip4200 printer did not complain about a
refilled cartridge, but it told me that it was completely empty and to
press the resume button to continue printing.
After printing a few pages, i powered it down and when starting a
printjob the next day it reverted to the "low ink level" behavior.
In the mean time it prints nicely with 3th party mangenta ink, without
ever showing the warranty warning and checking the ink level is a snap.
Have fun, Bert