!
error Brother
Error Code Drum - Yellow LED (blinking)
Drum unit has reached end of life.
? What Causes This
Drum unit is no longer usable and must be replaced.
✓ How to Fix It
Replace the drum unit assembly immediately. See User's Guide Chapter 5 for replacement instructions.
Source: page 5 of the official manual
From the manual
This error code appears in:
Brother HL-2000 Monochrome Laser Printer