Thought this might be helpful to others.

We've had a couple of Oztent camp chairs for around 2 years, and after about the first year they started getting "sticky" to set up and collapse.

Finally it annoyed me enough to do something about it. Basic issue is that they have plastic sliding pieces that gradually accumulate dust etc and start binding on their mating surfaces.
One of the chairs even had sort of galled lumps of plastic built up on the metal parts. A quick rub with some scotchbrite and a squirt with some dry teflon spray (like Selleys Ezyglide) on the sliding areas has made them work smoothly again
Make sure you also spray under the arms where there are blocks that slide inside them.

I'm guessing that if you gave them a spray when new and then every 6 months or so they would never get sticky.

Like everything else around your vehicle/campsite don't be tempted to use silicon spray as it collects dust/grit.

Steve