1/2 inch track

Hi-I have bifold doors that are on an old 1/2 inch track. Something happened to the piece that goes into the track that holds the pet in the top of the door. The handyman that was out today said that he thought that the old 1/2 in track is no longer made and parts may not be available. Can you tell me what my options are? I am attaching a picture of the track. Thanks so much.