Metal bi fold door hardware and lower track
Thanks for reaching out. You have the old Slimfold bi-fold doors. These exact pins are no longer, so they'll need to be replaced with the newer style.
For this repair, you'll need one 21-001 Bi-fold Door Pivot Assembly (to replace the bottom threaded, adjusting pin) and three 21-007 Bifold Door Guide Pins, which will replace the spring loaded pins.
You'll need to use one of the bi-fold tracks, tagged below this thread, to replace the tracks. To determine the best fit, be sure to measure the length of the existing tracks/door opening.