It could be the hose that just vents to the air , look at this picture , note the hose clipped onto the hose going to the valve cover , it also shows the T fittings and hoses connected , trace those and see if you have yours set up like the picture , this should guide you to what hose is not connected on yours
Also , the best way to connect the Hot Start is to twist the carb to the right by loosening both hold down clamps and grabbing the top and pushing it to the right , it will only go so far , but it should be enough to guide the Hot Start button into the carb and snug down the nut , just as twisting to the left makes installing and removing the throttle cables , no need to lift the subframe and remove the carb by doing it that way