Old bifold closet doors

A quick learner from NYC says:
I'm in an old NYC apartment with older bifolding closet doors. I was trying to make the doors close better, but upon inspection, they are different than bifold closet doors I'm used to. They do not hand at the top, but just roll in a track at top and bottom (pictures are from bottom). The bottom part seems to be the problem. It looks like there are just nuts on the screws at the bottom that are used to glide on the bottom track ? I'm doubtful this was the original hardware.

What kind of part do I need here for these doors to glide properly?
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Paul from SWISCO responded:

Many thanks for your correspondence. My guess from your photos, you might have a Paniflex bi-fold doors. They are very popular in NYC. If that's the case, then the bottom corner threaded adjusting pin would be our 23-101. The top pivot pin would be our 23-100. Finally, the top and bottom spring-loaded guide pins would be our 23-099. Please compare and let us know your thoughts.

A quick learner from NYC says:
Thank you for the response, Paul. 23-101 looks similar to what is being used in the bottom corner. However, the guide pin also looks very different (the first/left picture I uploaded is what is being used as the guide pin currently, the right-side picture is the bottom pivot pin).

I've added a couple more photos to make it more clear. One is of the full bottom of the door, and the other two are the outside and inside of the bottom guide pin. The bottom guide pin seems to be what is working particularly poorly, perhaps it's the wrong part being used currently?
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Paul from SWISCO responded:

We have a similar bracket, our 23-101. However, we don't offer a nylon cap that will lock on the pin end. Have a look at our 21-100 and 21-006. There may be a chance one of these could fit on your pin. Get back to us with your thoughts. 

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