ssldr1

I'm new to the board but I'm sure its not a new problem. My 92 Legacy with pneumatic suspension appears to have an air leak on the front left. It went flat after I parked it tonight. I started it up, the car rose again but after I shut it off you could hear the hissing as it went flat. Will this require the entire suspension in the front to be replaced? Does it have to be pneumatic? Can only a Subaru dealer take care of this? $$$? Thanks for any insight you can give. ssldr