1970s metal bifold door bottom roller pin guide

Metal bifold door, the cap is broken. This is a picture of a different pin in the same home where the cap on the pin is intact.
Pin measures about 4 5/8 inches. Door catches about 3 inches before closing and feels like it's gonna break if I pull it any farther closed.

Thank you for your reply. I have tried several pins with caps that looked similar but they don't fit. The problem was with the cap being broken, the pin would fall below the track and get caught on a metal bracket as it was nearly closed. I was able to hot glue a plastic washer onto what was left of the brim of the cap. Effectively creating a new brim , so that the pin could ride along the top of the track rather than fall through. This is working really well.