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Canon imageCLASS MF720C Series (mf726cdw) -- adjusting gradation results in "correction failed"


I had been struggling with print quality for quite some time on my mf726cdw, with colors printing very lightly. I updated the firmware and reset all settings recently, and to my surprise my prints all of the sudden looked fantastic!

Sadly, I enabled auto gradation adjustment on startup, and found that the adjustment brought my quality back to being super poor.

Recently, I discovered that trying to run the gradation adjustment procedure (both full and quick) fail with the message "correction failed" and I'm betting that it's also been failing at startup, resulting in the incorrect gradation settings being applied automatically.

I went through the manual which gives the suggestions:

If the <Correction failed.> message is displayed
Did you load plain or recycled A4 or Letter size paper into the paper drawer?
Did you place the adjustment image with the print side face down, with the black stripe toward the back side of the machine?
Has a paper jam occurred?
Is the amount remaining in toner cartridge required for correction sufficient? If the amount remaining in a toner cartridge is low, it is recommended that you replace toner cartridges.
Is the transfer belt inside the machine dirty?
- I have loaded plain A4 paper
- I placed the image face down with black strip toward the back of the machine
- There is no paper jam
- My cartridges are all >50% full
- I cleaned the ITB twice
I'm looking for help on how to get this working; otherwise this printer is only useful for B&W prints 😕
Some questions I have:
- How can I troubleshoot and fix this failure?
- Is it possible to adjust the gradation manually on this model?
- If not, is it possible to flash the mf729cdw firmware so that I can manually adjust it?
- As a workaround, is it possible to reset the firmware to default setting so I can at least use the default "good" gradation settings (along with disabling auto-adjustment)?


Bump on this -- I did a factory settings reset and it didn't seem to help. I am running 3rd party cartridges but I'm not going to spend $200 to find out if canon catridges can fix this...

Hello Ethereal,

The genuine toner cartridges have chips on them that provide the printer with toner level information and allows print quality adjustment. We can only suggest the use of the genuine toner cartridges since we have the specifications for our toner. Third party toner can cause print quality issues and problems with adjusting quality and performing maintenance functions.