maybe an exploded picture would help...
http://oldcarmanualproject.com/manuals/Carbs/Rochester/2-Jet/Manual/Part2/MCarbRoch73802GPart202.jpg

you can see the ball, spring, and the retainer that holds it in (parts 42, 43, 44). All of this is under the venturi cluster (part 38). The model in the picture does not show the ball under the accelerator pump. Hope this helps...