Brother MFC-3420C - Manual (Page 163)

13 - 16 TROUBLESHOOTING AND ROUTINE MAINTENANCE
5
Attach the yellow protective bar.
6
Remove the paper tray and output paper support.
7
Wrap the MFC in the bag and place it in the original carton with
the original packing material.
If you are packing the MFC for the Brother Exchange Service,
keep these items and return only the machine.
Protective
Yellow Bar