The part that wears out is plastic, after all. Logically it could be the age of the plastic and other factors that can make it happen.
Practically, I don't know. Just that the sources I read about this were professionals that repaired and used Canon A's for a living. Something about a bushing wearing out. They would always take an extra bushing on assignments for replacements in the field.
I call BS at the idea of replacing bushings or gears in the field.