So you got a $800+ office chair for next to nothing! Great, but look at those arm caps :(.
Don't fear, you don't have to cough up $80 for new ones, just print them yourself.
Step file included if you need some modifications.
Print the stl file with the orientation supplied.
No support needed. (I tried both with and without support, you will still have to clean it up a bit.)
Remove the old outer plastic, it will look like the photo in the middle.
Place the rubber inside the new cap.
Fasten it with double sided tape to the chair. I didn't see the need to over complicate the design, it still looks good.
I have not been brave enough yet to try TPU, please let me know if you tried it out.
The author marked this model as their own original creation.