You point out a perfect conclusion to WD40’
It is not a lubricant, its a cleaner- to degrease.
I have done mechanics for years.
As Bob mentions, you do not lubricate ladder parts you adjust them.
By lubricating parts you destroy them faster. They are none lub-parts.
Clean with soap and water , I use my industrial pressure washed and the adjust the components with a key or crescent wrench.
Bushings are nylon and never over tighten.
Observe for ware on all moving parts and replace any bent or damaged parts with NEW parts only.
Feet and locks are easy to change and do not over or under tighten.
When you are at the hardware store, look to see how the new ladder parts move and examine your for differences.
Wow my Mr.Dad was an alcoholic and a knuckle head but an architect.
I know what not to do after seeing him in action.
To bad I learned the hard way.
My tele-steps are 5 years old, used thousands of times, and never a breakdown. Only problem is that I have gone through 4 sets of rubber feet. I do periodically lube with silicone. WD-40 should not be used for anything but rust removal. It eats nylon. A new product out there is Liquid Wrench Dry Lubricant spray. It leaves a dry powder that is barely visible, and no residue. I use it on my show car. Expensive, but it drys clear. Main ingredients are Heptane and propanol. Good for windows, drawer guides, hinges, locks, etc.
My Extend n Climb has got to be getting close to 10 yrs. Still use it every week. Clean it with a microfiber cloth when closing it up. Never had a single incident. Just make sure when extending that it fully engages the locks. Use it in accordance with instructions. Most (ladder) accidents are caused by “pilot error”. I am sure there are cases of faulty equipment. The biggest danger I have experienced is getting the dog crap pinched out of a finger or thumb when closing it up and it was my fault, not paying attention to where I had my fingers. That particular error has a very short learning curve. Only done it once and my finger hurt for three days.