I see this is an old post but I didn't find one with more info to bump.
I'm playing with my first pump that has the idle bump connected to the cold start lever.
This is a pump I pulled off a car at the salvage yard.
It was missing the spring on the end of the governor, I think it's called the idle spring.
I grabbed one from another pump and put it on the one in the picture.

So my first question is are these supposed to have an idle spring?
... because inside:

where the screwdriver is pointing,... there is no spring.
You can see the hook the small idle-bump spring connects to, the one that gets pulled when the see-saw idle is adjusted.
There has always been a small spring between that lever,
which below holds the ball which fits in the collar,
and the lever the accelerator springs hold onto,
which is moved with the residual fuel screw.
I'm having trouble adjusting everything for more power and a low idle.
I can get it to run good but can't get any black smoke or power anywhere above midrange.
Usually I'd turn in the max fuel screw and back out the idle.
The idle is adusted by the 7mm cap nut on the rod going down to the cold start lever.
By the way when you turn the cap; the whole rod is supposed to spin.
I'm not sure what threads into what, if it threads into the plastic at the base.
Idle also limited by one of the lock-nutted screws above the see-saw
and on the back of mine there is a torx bolt change the change the relationship between see-saw and the cold start rod by allowing it to slide in the adjuster slot.
This pump's adjustment change more than just the max fuel and idle.
I swear some times it misses like the timing is retarded when revving.
A few adjustments and it'll smooth back out,.. but I still can't get black smoke or enough power.