First step is to take it to a skilled subaru mechanic to figure out what exactly the issue is. Nobody can diag this for you over the internet, we can give you the common causes of this problem, but from there you've gotta do some research and/or talk to someone who has fixed these before. It isn't a terribly hard repair for someone who knows what they're doing, take it to a hackjob and you'll get a pile of junk back. So yea, never trust someone who isn't a skilled mechanic...
I don't know what intermediately skilled means, but I sure don't want them touching my car!