My Boeing experience is limited to 757/767 but I remember when a capt's seat broke and had to be replaced we were told that it had cost as much as a good model BMW.
I found they were tolerably comfortable when the cushions were new but unfortunately the company had no routine for replacing them other than on a major check.
I suggest you make a tech log entry for replacement.
As an interim try swapping the cushion for the one from the jump seat though you may find someone else has thought of it first!