WWII Japanese Military Key

Oki Denki (Oki Electric Industry) logo.  My understanding is that this is written in the old style with characters from right to left.  

Oki is a technology company with a suprisingly long history,  See: Oki Electric  This is of special interest to me , as I used to work for Oki Semiconductor, a modern US branch of this company.
Date is June 1943, the 6th month of the 18th year of the emperor's reign.  I'm seeking translation of the rest of the characters and the meaning of the stamped images.
Tags by the switch hole say something to the effect of "front seat" and "back seat."
My translators had trouble with this:  "For No. 2" and "For No. 3"  I don't know what that means.  I was guessing it indicates normally open (left) and normally closed (right) as that is the function of the adjacent terminals.

Wax (?) stamps on the inside of the lid.  There are similar ones on the key base.  Is it safe to assume this was navy property?
Key with substitute knob and switch.
Picture of a similar key from the Smithsonian Air and Space Museum website.  They don't give much detail:


Country of Origin: Japan

2 3/4 IN. High 5 5/8 IN. Long 3 1/4 IN. Wide


Physical Description:
Green painted metal, rectangular shape, black knob key, metal switch, black with silver data plates, 3 total