Vintage 3 Speed Shimano Shifter

I fixed an old three speed bike and I have an old 3 speed Shimano shifter. The cable was rusted and I thought if I open up the shifter I can clean the cable and make it work. Unfortunately I unscrewed the screw of the shifter and everything fall apart but I still have the parts and now I can’t figure it out how to connect it again. There is a ball inside.Any help would be greatly appreciated!

Thanks, Iris