Well, how about starting by describing where the parts in post #1 originated and how they were disassembled, because the parts in post #3, bare little resemblance to those in post #1.
THe first pic in my third post goes goes down the vertical overflow pipe and the second pic, which would have a circular drain stopper on it would go into the drain and some how link into the spring part. I can only assume that;s how they were attached because when the lever on the overflow stopped closing the drain, I removed the parts.
After doing some research, I've decided it would be easier to simply install a pop up drain-stop and do away with the old system.
Installing a step-toe drain stopper, is a solution, however, also remove the lever and drain stopper from the escutcheon, in post #1, and reinstall just the chrome escutcheon, or any high water will flood the area under the tub.