Canon imagePROGRAF GP-4000 Online Manual page 927

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Cause
The print head nozzle may be blocked.
What to Do
Follow the steps below to repeat Print Head Alignment.
1. Tap OK on the touch screen to dismiss the error.
2. 2. Print a test pattern to check the nozzles.
Checking for Nozzle Clogging
3. 3. If the nozzle is blocked, clean the print head.
Cleaning the Print Head
4. Repeat Print Head Alignment.
4.
Automatic Adjustment to Straighten Lines and Colors
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