Freud;
I have never seen one 'worn out". They are usually damaged by mishandling well before that. Some are ruined by epoxy or sealant, they are dropped on the floor and bent, or pulled out without being fully depressed, which wears off the undercut shoulder. Of course they can even be left out to rust-- poor workmanship can ruin an anvil, after all.
Taken care of, a Cleco should last a lifetime.
Regards, Neil Tucson, AZ