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H7943 /H7944 Framing Nailer
-12-
Replacing
Pistons/O-Rings
If you need to replace piston parts in your
nailer, you can purchase a piston repair kit
from Grizzly.
The Piston Repair Kit part number for
Model H7943 is PH7943087. The Piston
Repair Kit part number for Model H7944
is PH7944087.
Refer to the parts breakdown during this
procedure to identify parts and their loca-
tions inside the nailer.
4. The top of the piston should now be
visible inside the cylinder, which is
housed in the head of the nailer.
5. Watch the discharge area and push
the top of the piston with your finger.
You will see the piston shaft slide
down the discharge area.
6. With a long flathead screwdriver or
similarly shaped tool, push the piston
shaft back inside the nailer until you
can grip the piston head and remove
it from the cylinder. (Be careful not to
scratch the discharge area when push-
ing the piston shaft with the screw-
driver.)
7. Clean all parts with an automotive
grade solvent. Make sure all ports are
clear and blow the solvent away with
compressed air.
8. Inspect for cracks and wear; replace
any part that is worrn or shows heavy
wear, then relubricate the tool.
9. Place a new O-ring on the new piston
and apply a thin film of the nailer lubri-
cating oil on the O-ring.
10. Insert the new piston in the cylinder.
Make sure that the grooves on the
piston shaft align with those on the
guide at the bottom of the cylinder.
DO NOT force the piston into the
cylinder! If the piston is not easily
inserted, double-check the alignment
of the piston shaft with the grooves on
the guide.
11. Replace the rear cap assembly and
tighten the 4 cap screws.
For more assistance with O-ring replace-
ment or other piston parts, refer to the
parts breakdown diagrams in the back of
this manual.
To replace a piston and O-ring(s):
1. DISCONNECT NAILER FROM THE
AIR SUPPLY!
2. Remove all nails from the magazine.
3. Remove the four cap screws on the
head of the nailer, near the exhaust
port, and remove the cylinder cover.
Always disconnect the air supply
from the nailer whenever servicing!
During maintenance, a nailer con-
nected to air may fire accidentally,
causing serious personal injury!