Since wood is a natural material, wood can expand and/or contract due to a variety of environmental factors. Traditional Kendama designs (like ours) allow for the Sarado (cups) to separate from the spike so that it can be re-strung. Firmly pressing the cups back down will usually fix the issue. If the cups become too loose, we do have a few tricks for getting them to stay: tear a small piece (about the size of your thumbnail) from the sticky area of a sticky note and apply it to your Sword (spike) before pushing the cups back into place. Double-sided tape, a small piece of tape that has adhesive on both sides, is a solid alternative. Both of these materials add some extra stickiness and width between the two pieces of wood and help the cups stay on the spike. Note: using super glue can permanently affix your cups to the spike. We do not suggest this.