I ordered a new gas lift for my 5 year old chair and Ergohuman kindly provided this tool as well. However, even with soaking it with WD-40 for several days this tool could not remove the lift from the seat base. Instead it now has deep gouges in the loose ring.
After a week of trying, I got a decent wrench from Bunnings and that did the job satisfactorily (no need for tape btw). The wrench also helped ‘wrench it out’ of the bottom base.
In the end I got myself a decent wrench from Bunnings. It did the job, no need for tape. It also helped me to get the gas lift out of the bottom base.
So I hope I won’t have to repeat this for the next 5 years.