Hitachi NR90GC - 3-1/2" Gas Powered Clipped Head Framing Nailer Technical Data And Service Manual page 27

Problem
<Output section>
Piston bumper is abnormal
(dislocated, deformed or
damaged).
O-ring [36] of the cylinder is
abnormal (dislocated,
deformed or damaged).
Driver blade is abnormal
(deformed, burrs, damaged
or fatigued).
2) Nails are bent For short nails, the adjuster
when being is raised too high.
driven.
Nails are not fully fed into the
injection port.
Unspecified nails are used.
Driver blade is worn.
Workpiece is very hard.
Nail Feeder (A) [112] is
abnormal (worn or
damaged).
Possible cause
Inspection method
Pull the nail feeder backward
and perform idle driving.
Check if the driver blade has
returned.
While operating the nailer
without nails, check if the
driving operation is
performed.
After operating the nailer
without nails, check if the
driver blade is kept in the
down position.
Check if the adjuster is raised
too high.
See item 1).
Check if the driver blade tip
is abnormally worn.
Drive a nail into soft wood
workpiece and check if the
nail is bent.
Check Nail Feeder (A) [112]
for abnormal condition.
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Remedy
Replace the piston bumper.
Reassemble or replace.
Repair or replace.
Replace the head valve
spring.
Turn the adjuster to the
lower position to decrease
the pressure.
See item 1).
Replace the driver blade.
Do not use unspecified
workpieces.
Replace Nail Feeder (A)
[112].