C360 Toner Supply Indicators always full

[Motormount]

Please tell me if anyone has seen this before or has a guess what it might be.
We picked this C360 up as a lease return with 48K total, about 6K color prints. Shortly after beginning testing we got error code C2553: Abnormally low toner density detected Magenta TCR sensor. We found the Magenta toner supply port empty, so a manual add filled the hopper. Checking the Machine Management List, we found 126 C2553s, so decided to replace the toner hopper assembly. That problem seems to be solved, as we've printed about 1000 pages of high-coverage brochures to make sure the hopper keeps up.
What has us worried is that the Toner Supply Indicators on the display panel show Full for all four cartridges, and have since we first powered on this machine.
There is nothing on the KM site about this, nor copytechnet.com, and nothing on these indicators in the manuals. Any ideas?
We have the latest base firmware (D2) and the Unit Life Optimized Settings invoked per the bulletin.
Thanks for your help.

[emujo]

My advice would be to ignore the messages, let the MFP run until you do finally get a "replace toner soon" message, then install new cartridges. If you experience copy quality issues (light) before you get the replace toner message, then you may want to replace the print control board. Emujo

[copier tech]

Yes ignore those toner levels icons, they are only estimates, & as said earlier only ever replace the toners when the machine prompts empty not nearly empty

[Motormount]

Yeah, we've had client's replace them early and they don't reset, but never saw them stay full.
You're right, Emujo and copier tech... we removed the black cartridge and ran it to shutdown and it dropped incrementally, then installed new cartridge and it reset to full. I'm guessing the previous techs that were troubleshooting must have had the cartridges in and out several times.
Thanks again for your input.