Hitachi UX Twin Nozzle Service Manual page 226

６ Remove the shutoff valves.(MV9/MV29)
(Refer to "5.5 Shutoff valve (MV9/MV29) Replacement")
７ Remove the 4 fastening screws of the heating unit.
Remove the head base rear cover. (14 screws)
８ Remove the two connectors and remove the heating unit.
９ Prepare the new heating unit and put O-ring 1.7 in the joint area
of the ink-supply tube (E).
Perform the assembly after dipping the O-ring in makeup, and
confirm that the O-ring does not jump out of the hole.
10 Attach the head cover and the heater cover.
MV9, MV29
Fastening screw
Head base rear cover
Fastening screw
Heating unit
5-10