Hitachi NR90GC - 3-1/2" Gas Powered Clipped Head Framing Nailer Technical Data And Service Manual page 56

(b) Reassembly
Fit Gasket (A) [23] in the groove of the Chamber Head [22] and mount it to the Chamber [24]. Do not
protrude Gasket (A) [23] from the groove. Be careful of the mounting direction of Gasket (A) [23] (Fig. 48).
* After mounting the Cylinder Ass'y [42] to the Housing [71], mount the Switch Plate [34] to the Chamber [24].
Note that the Cylinder Ass'y [42] cannot be mounted to the Housing [71] if the Switch Plate [34] is mounted
to the Chamber [24] first.
Chamber Head [22]
Gasket (A) [23]
Convex portion of
Gasket (A) [23]
Fig. 48
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