I had a telescoping ladder ,it was fine until it got scored /damaged ,the locking mechanism then became unreliable.
A light sanding /smoothing helped for a while ,all in all is was too easily damaged and a tiny scrape rendered it dangerous .Once it started to retract while I was on it ,my hand was trapped by a rung and the roof of the trailer ,my weight prevented me from freeing my hand which was jammed .
kind of funny now
scrapped it ,(we called it the ladder of death)