Hitachi NR90GC - 3-1/2" Gas Powered Clipped Head Framing Nailer Technical Data And Service Manual page 40

(2) Disassembly and reassembly of the Top Cover [3] and the related parts
[Tools required]
Roll pin puller (2.0 mm (0.078") dia.)
(a) Disassembly (See Fig. 29.)
Remove the Filter Cover [5] and the Filter [4].
Remove the Shaft Ring [26]. Then remove the Shaft [27], Washer M5 [2], Cell Lever [105], Cell Rubber [110]
and Cell Cover [109].
Remove the Roll Pin D2 x 8 [107]. Then remove the Latch [106] and the Spring D3.6 [108].
Remove the Adapter [30].
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