I have had several of these pop socket prongs break on me. This ring fits inside the circle on the back of a pop socket cap.

You will be required to cut out the old prongs then glue this piece in place. I just used 4 dots of super glue.

I included the SolidWorks part file

Notes about printing: Print prongs side down Since they are only about .8 mm tall I would recommend using a low layer height. I used like .2mm in hopes that would give the prongs structure. The print took about 5-10 minutes. Mine warped a bit because of poor bed adhesion but it worked just fine.

1 Month Update: I couldn't be happier with this repair. the cap fits better than the original. The insert makes the cap a little bulkier which made it fit better in my pop socket mounts.