Brother MFC4820C Service Manual page 92

(6) Pull the latches on the left end of the print head unit outwards and remove the paper width
sensor cover.
Latches
Paper width sensor cover Print head unit
(7) Take the paper width sensor out of its support in the print head unit ( below).
(8) Unlock the FPC connector ( ) and disconnect the head flat cable from the print head unit ( ).
Head flat cable
FPC connector
Print head unit
Paper width sensor
Sensor support
6 -7