I'll assume you have a 91 to 94 Legacy. The entire suspension can be replaced with a conventional coil spring suspension. A simple remove and replace process.
May want to test a few things before going this route. Disconnect the air line at the strut. Be careful peeling back those plastic lock tabs because they will break if bent too far. The strut will immediately deflate. But the compressor should activate and you should feel/hear a strong flow of air coming from the disconnected line. Not wimpy puffs but a good flow. Do this for each strut.
If you have a good flow of compressed air at each strut then you know all the system up to the strut solenods is good. Now all that can be wrong is: The solenoid is leaking, the air line between the solenoid and strut is leaking, the air line fitting at the strut is leaking, or the strut has a hole. Everywhere an air line connects to something there is an O-ring.
Soapy water can be used to detect leaks.
Last week a set of air struts (23K miles) sold for slightly less than $200. They don't appear very often but several times a year someone sells a set.
I really doubt if you will find anyone that can rebuild these struts. They fail 99% of the time because the airbag either cracks or gets a hole. I've never been able to find anyone that has these bags.