I ordered a replacement gas strut of amazon (
pretty sure it was this one). It extends a little longer than the original, and has a higher weight rating. Been great so far.
It can be a bit of a pain to remove the old one though. Normally need a hammer/mallet & a pipe wrench (the guide videos make it look easy, as there's never been any weight squashing it all together!)
I can't remember how long I've had my chair for now, but it's definitely been a good few years! Only had a couple of issues myself:
1. the front of the cushion has a metal bar along the width (presumably to help keep the shape), but this broke out of one end, so I kept catching my leg on it. I've since removed it & don't have any issues with it.
2. The arms are a fixed height. I think my next chair will have to have height adjustable arms. To have my chair at the height I want it, the arms hit the front of the desk (I have a corner desk) so I can't then sit as close as I would like.