Canon LBP-1760 Service Manual page 194

CHAPTER 4
M-30. "DUPLEX JAM" message appears when the paper jam has not occurred; so, the
printer cannot be in READY mode.
<Possible causes>
1. Reversing paper sensor lever does not move smoothly, or is damaged.
Action: Set the lever to move smoothly. Replace it if damaged.
2. Duplexing unit pick-up paper sensor lever does not move smoothly, or is damaged.
Action: Set the lever to move smoothly. Replace it if damaged.
3. Defective reversing paper sensor
Action: Replace the sensor.
4. Defective duplexing unit pick-up paper sensor 1
Action: Replace the sensor.
5. Defective duplexing unit driver PCB
Action: Replace the duplexing unit driver PCB.
6. Defective engine controller PCB
Action: Replace the engine controller PCB.
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