Oki LP-1040 Maintenance Manual page 642

(3) Main scanning direction straight line chart: One position
<Items to Check>
Missing dots, caused by the CIS sensor's defects or foreign particles
<Check and Criteria>
Check that the straight lines are not disconnected at the sensor connection part.
When the straight lines are not disconnected, the results are OK. If any disconnections are
found, the results are negative.
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