I thought I saw something in the service manual about "winding up" the spring a bit, so that it's preloaded and starting to move the riser valve when cold. But I just looked and can't find it. In other words, put the tang in the slot on the shaft 180 degrees from where you show it in your last photo, and then pull the outer tang over the stud. The spring doesn't really push that hard, which is the reason for the counterweight.
