LOL, my google search came up with that list too, and an airbrush artist that does amazing work with your Wren A. She's the one who said that it was discontinued and parts were hard to find.
An old internet trick of mine is to just enter binks.com and see what comes up. Lo and behold it was the Binks Airbrush company!! A search on that site got me to the Wren B model.
Good luck!