Canon MG7700 series Online Manual page 1098

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Cause
Protective material or tape may still be attached to print head holder.
What to Do
Open the operation panel and make sure the protective material and tape have been removed from the
print head holder.
If the protective material or tape is still there, remove it and close the operation panel.
If this does not solve the problem, contact your nearest Canon service center to request a repair.
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