Hello, please refer to the following:
1. Check if the toner in the toner cartridge is depleted (view by printing a configuration report page, under Consumable Information - Toner Remaining). If the toner level is low, it will affect print quality; please replace the toner cartridge.
2. Confirm that the sealing tape on the drum unit has been removed. It needs to be completely pulled out and removed.
3. Shake the toner cartridge 5 to 6 times to evenly distribute the toner and improve print quality.
4. Perform a cleaning mode operation.