How do I Repair a Senco SN65 Nail Gun?

Written by mark morris
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How do I Repair a Senco SN65 Nail Gun?
With a properly sized Allen key, a hammer and punch you can rebuild your nailer. (Stockbyte/Stockbyte/Getty Images)

The senco SN65 is a framing nailer capable of driving up to 3 ½ inch common nails. It is pneumatically driven by any standard compressor and can be fitted with a standard male quick connect air nozzle to fit most standard air hoses. The main issues with most nailers have to do with the control of air flow. Senco offers kits to replace the seals in the plunger cylinder and trigger valve, as well as replacement drivers, which can become bent, particularly if air pressure is inconsistent.

Skill level:

Things you need

  • Ballpeen hammer
  • Metal punch
  • Trigger valve assembly parts
  • Allen key
  • Driver cylinder assembly parts
  • Tool oil
  • Cotton swab

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    Trigger Valve Replacement

  1. 1

    Place your Senco nailer on a flat, sturdy surface on its left side. Locate the small roll pin directly above the trigger assembly. Use a ballpeen hammer and small metal punch to drive the roll pin from the right side of the nailer to the left, until you loosen the trigger. Remove the entire trigger assembly, sliding it toward the nose of the gun.

  2. 2

    Pull the trigger valve assembly from the handle of the gun, in the opening behind the position vacated by the trigger assembly. Use a flat screwdriver to pry it lightly, if needed. The O rings on this part are individually replaceable. Inspect them for wear and replace only damaged seals, or replace the entire assembly if signs of damage, or wear are present, or the trigger has a hard time rebounding once pulled.

  3. 3

    Oil the seals on the trigger valve assembly with air tool oil on the tip of a cotton swab. Insert the valve back into the handle of the gun, aligning the groove and flat edge to slide it in. Press it firmly into place. Reinstall the trigger assembly, sliding it in from the front of the gun. Tap the roll pin back through the hole in the trigger with the metal punch and hammer, using light taps to prevent bending.

    Driver Cylinder Replacement

  1. 1

    Remove the four screws holding the square rear vent onto the back of the gun above the handle, using an Allen key. Remove the cover. Pull the round, white cylinder from the gun. It contains the driver assembly.

  2. 2

    Inspect the seals and replace just the seals, or the entire assembly as outlined previously for the trigger valve. Remove the driver from the front of the old assembly and replace it if it appears bent or grooved. Reinsert the driver into the cylinder and slide it into the chamber, aligning the notches on the sides for proper installation.

  3. 3

    Replace the cover on the rear of the gun and install the four mounting screws. Apply three drops of oil into the air inlet fitting on the bottom of the gun, then reattach the air hose and return the tool to normal usage.

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