Brother HL-5280DW - Manual (Page 112)

7. Troubleshooting
104
JAM DUPLEX (Paper jam in the duplex tray)
JAM DUPLEX
If a paper jam occurs inside the duplex tray, follow these steps:
a Pull the duplex tray completely out of the printer.
b Pull the the jammed paper out of the printer or the duplex tray.
c Put the duplex tray back in the printer.