Hitachi NR 83A2 Technical Data And Service Manual page 27

Problem
Plunger O-ring (inside the
5) Single
valve bushing) is abnormal
actuation
(worn or broken).
impossible.
O-ring (P9, inside valve
sleeve (A)) is abnormal
(worn or broken).
6) Piston O-ring (inside dia. 10.7) at
actuates just the outside of the valve
by pulling the bushing is abnormal (worn,
trigger (when damaged or broken).
single
actuation is Gasket (G) is abnormal
selected). (improperly mounted, worn
or damaged).
Possible cause
Inspection method
Set the single actuation/
contact actuation selector to
the single actuation.
Perform idle driving once
and keep the nail feeder
pulled backward. Check that
no air leaks from the inside
of plunger (B) and valve
sleeve (A).
Disassemble the control
valve and check the O-ring.
Disassemble the exhaust
cover and check that gasket
(G) is normal and mounted
properly.
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Remedy
Replace the defective part.
Replace the defective part.
Mount it properly or replace
the defective part.