I don't like the look of that first picture. I just opened up two sets of controls for my JohnnyRudes this past week, I don't remember seeing a point in the cam action where the follower was exposed like that. Use the model year to find an exploded view. There are a few other sites that have nice exploded views of the controls that you could use to compare that part.
Just to confirm; When you open the controls, you can move the throttle both forward and backward by moving the cam follower by hand? Or are you only able to move the throttle back into position under the motor cover?
If it can be moved forward and backward manually by moving the cam follower, then it's a problem with the cam mechanism.
If it can only be moved forward and backward under the motor cover, then as mentioned previously, it's probably a broken cable.
Good luck!