Hitachi CHROMASTER 5160 Instruction Manual page 159

(9) Install the new wash mechanism seal in the bearing of the
wash mechanism plunger guide.
(10) Tighten the seal holder with the wrench and the flathead
screwdriver.
Seal holder
Bearing
(11) Install the plunger wash mechanism and the pump head on
the main body of the pump. Put the plunger wash
mechanism into the plunger while rotating it to the left and
right gently.
The direction of the flow path of a plunger is shown in the
figure.
(12) Next, install the pump head on the main body of the pump
as guided by the guide pin.
(13) Fix the pump head. Two hexagonal screws are tightened
up lightly with the hex wrench. Next, tighten alternately two
hexagon screws little by little (about 30° each, 4 to 5 times)
with the hex wrench to secure the pump head.
NOTE: Tighten two hexagon screws equally to prevent wear of
a seal and damage of a plunger.
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Wash mechanism seal
Bearing
Flathead screwdriver
Wrench17