The pliers of this young woman were always in good condition, but the rubber sheath that covers the handle was damaged. She completely removed the sheath and put a whole new one. What she used as rubber is amazing, but it works:
A balloon !
She inflated an elongated balloon without knotting.
She then inserted the balloon into the handle of the pliers.
Then she released the balloon to deflate.
She cut the surplus.
And here it is!