Ross, I had a very lucky escape once with a triple extender. The ladder had blown over some months before and had left a small dent on the underside of the bottom section. I was on it one day and it didn't feel right, on examination it had cracked from the dent and down both sides. A mate of mine had one break under him [lucky no injury]. He had a ladder rack on his trailer. it snapped where the ladder had been in contact with the rack. I also had a ladder made by one, if not the leading manufacturer. It had square rungs. these rungs became a sloppy fit in a very short time. A client of mine, who's duties included inspection of fire service ladders, told me he had scrapped better ladders.
I had to take it back to the retailer who exchanged it for a LYTE
ladder. This has been excellent, rigid and robust. Inspect them. Any dents disscard them. I have used wooden ladders with alloy rungs for every day work since, still do if I can't WFP them DAI.