I had to replace 2 on an old xylo that had broken off.
The lower stem was very hard to remove since it broke off level with the surface of the support.
But once I got them out, the new pieces fit well and should last forever.
I'd give it a 5 if it was designed originally so that the pieces could be replaced more easily. Perhaps a screw in design.
Musser open end posts.
Shipped so very quickly, and cost only 1/3 of the nearest competitors price!