I keep those things on hand always. I buy them buy the 10 packs on amazon because I’ve stretched them, warped them, bent them so many times in the past on other machines. Alot of times when I’d buy a budget 3D Printer, those things would always get messed up in transit because of the way the top part of the frame would be packaged, so As soon as I unboxed, that was one of the first things I’d change. And when they need replacing, I’ll take the grub screws out, save those and chuck the couplers.