If it’s like some of my black small Mercs, (and it sure looks like it is) #19 is a single screw, who’s edge just overlaps the edge of a bushing. That bushing is part of the throttle shaft assembly, that should now pull straight out. Admittedly, sometimes that bushing can be a real fight to pull out. You can latch onto the “paddle” part of the linkage with vise grips and pry on the vise grips with a screw driver. #18, which seems to be the part you’re describing as broken, should pull out. You shouldn’t need to have to pull the pan or the tiller support bracket, which is a much more major operation.
Long live American manufacturing!
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