I used to could tell you but my manuals are gone and I forgot. The key assembly should have a nut attaching it to the case of the controller. Take the key and turn it to something besides OFF and pull on the key assembly....pull it back slightly from the case of the controller and check out the threads on the side of the key switch housing. Going to be a fine threaded Spanner nut of 1" or so that you might find at a hardware store or a Marine dealer if you have one nearby.
Once you get it locked in place with your nut, pushing in on the key, with the outer key housing not moving now that you have a nut on it, activates your electric choking device. Procedure is to put the gear shift in N, you may have to wiggle the handle a tad but locate the square button on the handle pivot at the bottom. With the control lever in N, depress the square button....if it won't go in most of it's length, wiggle the handle so that it does and keep it depressed......move the handle forward as if you were shifting to F gear....but you won't be, you will only be advancing the throttle.....once you have moved the lever a few degrees forward of N, the button should stay pushed.
The previous procedure is your "fast idle" function and is an aid with depressing the ignition key in getting the engine started........think about the old days of carbureted auto engines....you pressed down on the accelerator which released the automatic choke whose butterfly partially closed off the carb venturi and also opened the throttle butterfly in the carb somewhat both as an aid in starting.
Once the engine lights off, release the key....keeping it in the ON position and ceasing to push it into the control box, and set the throttle to a comfortable rpm....I like 1-1.2k RPM and let it warm up. Once warmed up, bring the lever back to the vertical N position whereby the engine will return to idle RPMs and the button will pop out......now when you push the lever forward, you are back to shifting to F gear and advancing the throttle.
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If you have to open the unit to access the switch, first off advance the throttle/shift lever fully forward....WOT position. Look at the underside of the bottom of the lever and there should be a hex socket set screw that locks the handle to the shaft that goes back into the unit. It is probably frozen but get it out and then pry the lever off the unit. There are 2 screws visible in your first picture on the face of the cover of the unit that, when removed, will allow you to remove the cover to the unit and access the inside.
As far as identification, that is the older type of single lever, general purpose combination speed/shifting control. There are two other, newer types, one with a big black, round button, for recessed boxes which requires the switch to be mounted elsewhere on the bulkhead rather than on the switch box and a second with exposed control cable and wiring bundle which has everything on the box including a Fast Warmup lever on the top which does the throttle advancing much easier and just requires the shift lever to be in the N position.
Once inside you will find 3 (as I recall) bolts which you can access the locking nuts from the rear of the bulkhead for assembly removal.
