At one time, there must have been a lever, or gear like mine,
attached to your broken throttle shaft.
Regarding the spring, it’s probably bent, or the end broken off.
One end is in a hole in the throttle shaft, and the other end
must have hooked on the carb body some how.
Hopefully someone will come along with better photos or knowledge.
Keep an eye out on Ebay for Flambea parts or photos of carbs.
Prepare to be boarded!
