The quills should be tapered, with a machined ball on the end, preferably hardened. If that ball is worn off, you will wind up with quill pecks or drops, when the quill jumps out of the socket on the back, slides off the back and hits the glass.
You don't want that to happen! It's a real pain in the butt, and will leave you with a ton of grinding to fix it!
M.