Brother EM-850fx User Manual page 202

6
[ ] Gently push back the right extension paper support to lock the right
paper support.
[7] Push down the paper tray button and bring it forward until it locks.
8
[ ] Set a stack of paper onto the tray.
Fan the paper before inserting it. Insert a stack until its bottom is tucked
under the right and left strippers. The tray can retain a stack half an inch
thick.
[9] Push the paper tray button backward to make it pop up.
Both the upper and lower paper tray buttons must be kept up for the
operation; even if the tray is empty.