I'm in the middle of restoring some Esterbrook SJs, and learning more all the time of course -- I will post photos of the final product, which I promise will be a set of lookers!
Wouldn't you know one of the J-bars was broken, and came out with sac pieces in a heap. There was something else in there I wasn't expecting, and thanks to other posts I've learned it's a spacer for proper positioning and to prevent the J-bar from creeping back into the barrel away from the lever's...lever-ing action.
In advance of jumping into pen repair I realized a strong and tiny LED light would be useful, and then I discovered they came with cameras attached
So here are some photos of my J-bar mess, followed by two with spacers in situ behind the J of the J-bar. Enjoy!
(I hadn't yet set the date or time on the camera!)