Tuning Airforce Texan SS .357 valve leak.

Merry Christmas everyone! Back with more questions. I'm 98% confident I've narrowed the leak in my texan down to part of the valve. The little... thingy on the end of the valve stem has a crack in it. Problem is I cannot find where to get a replacement for this dumb little plastic whatsit. I've attached a picture showing the part. Anyone have any ideas? I should I just pony up and buy a complete higher flow valve?

Inkedtexanvalve_LI.1640554207.jpg


Thank you!