Prevent pivot rotation

In the attached image I show a highlighted sphere. It is a child of the arm highlighted in the second image. The arm is at the end of a scissor mechanism. I want to prevent the pivot point of the sphere from rotating as the sphere travels with arm as the scissor mechanism moves up and down. However, I can not figure that one out. Simple constraints require a path. And pivot constraints lock location as well as other attributes. Should be easy. What am I missing?

Hello - I guess this is a Bongo-related question, maybe, is that correct?