Banister Pole Insert

So in my house we have a spiral staircase. The Banister are metal poles connected to main banister rail via a large plastic hinge.
Due to my children swinging down the rails like monkeys some of lower plastic connectors are broken.
There are no identifying markings, logos or serial anywhere on the structure so I do not have a clue to the make / model / manufacture of my staircase and after months of searching could not locate the replacement part.

So in the end I decided to have at go a m