Hitachi WH 12DM2 Technical Data And Service Manual page 41

(e) Mount the DC-Speed Control Switch [38] <35> to housing (A) so that the protrusion of the forward/reverse
lever at the top of the switch is inserted into the hole of Pushing Button (A) [39] <36>. Apply silicone
grease (KS609, Shin-Etsu Chemical Co., Ltd.) to the contacting surfaces of the FET of the DC-Speed
Control Switch [38] <35> and Dust Guard Fin (A) [29] <26> then mount them to housing (A).
(Note) The temperature of the FET may be high if the silicone grease is not applied. Make sure that the
three internal wires from the FET are passed above the DC-Speed Control Switch [38] <35> (see
Fig. 11).
(2) Apply silicone rubber (ThreeBond 1211) to housing (A) and Inner Cover (A) [25] <22> as shown in Fig. 11.
Mount housing (B) and secure them with seven Tapping Screws (W/Flange) D4 x 20 (Black) [33] <30>.
Wipe the silicone rubber coming out of the housing with a cloth. Insert the Sleeve [46] <42> into the Strap
[45] <41> and tighten the Machine Screw (W/Washers) M4 x 25 [47] <43>.
Position the blade of Dust Guard Fin (A)
[29] <26> under the rib of housing (A).
(3) Mounting the mechanical parts
(a) Mount Hammer (D) [12] <9> containing the twenty-eight Steel Balls D3.175 [13] <10>, Washer (J) [14]
<11> and Hammer Spring (D) [15] <12> to Spindle (D) [18] <15>.
(b) Align the top of the cam groove on Spindle (D) [18] <15> with the steel ball guide groove on Hammer (D)
[12] <9> as illustrated in Fig. 3. Press down either of the raised faces of Hammer (D) [12] <9> with a hand
press to compress Hammer Spring (D) [15] <12> until the end surface of Hammer (D) [12] <9> contacts
Spindle (D) [18] <15>.
Fig. 11
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Apply silicone rubber.