First off, I would highly suggest you not use a pipe plug in lieu of straight-thread plugs with washers. Those carbs are fragile castings. A pipe plug is tapered and puts side pressure on the threads and will bust the casting. On the areas where there are jets, the threads are for the jet, and the plug is the same thread. If you use a pipe plug you will change the thread pitch and never be able to remove the jet.
My motors are in a warehouse and as soon as I can, I’ll take a picture of the air horn and its choke lever. But, here is the page from the parts manual…The choke quadrant is shown and has a, for lack of a better word, cover that has a detent in each end. The choke lever has a spring-loaded pin that pops into the detent to hold the choke lever in either the on or off position. Both are usually broken. Art DeKalb used to make the castings for those.
I have placed arrows to indicate the parts and also an arrow showing where the spring-loaded pin goes.