It is fairly hard plastic. I just do not know how to gauge it. If you have ever seen a plastic nut and bolt, that is what I would compare the hardness to. I would do it for free, but I would need all of the measurements, or you could send me the broken part.
Even if you can find the part somewhere, perhaps you would consider still sending I to me. I would enjoy the challenge, and we could compare the quality, hardness and usability.
PM me for address if interested.
