Hi Mark,
excellent article! Time for me to finally resubscribe to lula now, I guess.
After reprinting some 3 years later, you found more significant dE value and say: "..., but I can’t explain the reasons for the shift in test outcomes."
I have a suspicion: If it was really the same printer with the same print heads, let's keep in mind that piezo printhead nozzles are subject to wear. Nozzles diameters increase over time, which should lead to higher volume ink droplets, and I cannot imagine that the printer has any means of compensating for this, unless you create a new profile, as you did.
Best regards,
Erik