Help! The Air Adjuster on my Seat Return Jet broke off

Here's a picture of the air adjuster that broke off my inground fiberglass pool wall, you can see the broken plastic around the edge. It won't stay on any longer so I'm unable to adjust the air coming out of my seat based return jet in my pool wall. I am also losing water out of the hole/mechanism that this covered. Where can I get a replacement one of these? Am I really losing water out of the hole/mechanism that this covered? Thanks!
Jon

https://dl.dropboxusercontent.com/u/...5/IMG_0983.JPG