S2A HELICOID PROBLEM ?

i was checking out the helicoid on my bronica s2a today and noticed the aperature lever in the helicoid does not rebound when moved.the stop down preview button/lever assy in the camera works fine, comes back to normal when button released.
my question is : is there a spring to keep tension on lever in helicoid ?i would think there should be.or am i just assuming there should be.have not shot any pictures yet just getting a feel for the camera.any thoughts??
thanks -- gary

My Bronica S helicoids do not have any springs, the aperture level depends on the spring in the lens for retraction.

Thanks for the reply.good info.i just got the camera a week or so ago.never had a mf camera before.just trying to research it as much as possible.
Thanks again