here's Don Wheeler's review:
https://sites.google.com/site/donsairbrushtips/Binks-Wren-Review
I looked on line this afternoon and parts are available, but they are expensive.
External mix airbrushes are an older design, but if Don says it works well, that's good news.
Clearly designed with binks' customers in line, industry. I'd thoroughly cleasn it with lacquer thinner, put it back together and see how it works. I personally probably wouldn't spend any money rehabilitating it as a brand new Iwata or Badger can be had south of $ 100.