Hitachi NR90GC - 3-1/2" Gas Powered Clipped Head Framing Nailer Technical Data And Service Manual page 51

Apply designated oil to the O-ring sliding surface in the Chamber [24] according to 10-1.
Be careful of the mounting direction of Pushing Lever Arms (A) [60] and (B) [62] (Fig. 42). Align the notch of
Pushing Lever Arm (A) [60] or (B) [62] with the convex portion of the Pushing Lever Connector [68]. Secure
the U-Nut M4 [59] with a spanner (7 mm (0.276")) or slender hd. pliers and tighten the Hex. Socket Hd. Bolt
M4 x 10 [61].
Pushing Lever Arm (A) [60] Pushing Lever Arm (B) [62]
Fig. 42
Mount the Chamber Stop Rubber [41] and the chamber ass'y to the Cylinder Ass'y [42]. Align the roll pin hole
of the Chamber [24] with the bent portion of Pushing Lever Arm (A) [60] or (B) [62] and drive the two Roll Pins
D3 x 32 [25] with a roll pin puller (Fig. 43). Use a pedestal when driving the Roll Pins D3 x 32 [25] (Fig. 44).
Do not support driving the Roll Pins D3 x 32 [25] on the buffer cover.
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