Try this
If i were you i would check the primary corona..
Or Potential control system.
Anoter easy thing could be the drum screw isnt tight.
Or the MSW2..
Disable potential control by going into service mode Copier>Option>Tempo>F-POT-SW. Now copies can be run.
1) A solid black copy means laser is defective.
2) A white copy means you should check the Primary corona and HVT pcb.
3) A good copy means you should check the Potential sensor PCB.
If it not is one of these things you are call technician.
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