Many of the Wacom drawing pens I’ve used over the years have failed in the same way, gradually developing a stress fracture within the plastic barrel. When that crack widens, the stylus’s internal circuit board can slip out of place and cause the drawing nib to retract unexpectedly.
That crack in the plastic casing leads to a mushy feel to the pen, loose enough to make the pen feel wobbly and unsteady. An unstable nib produces unreliable drawing results, spewing digital ink all over like an irritated cephalopod.
Unsightly, but effective.
Other stylus models like the rotation-aware Art Pen don’t seem to be as susceptible to such a break, though the inner structural design looks identical.