[NiftySVX]

The Transfer control solenoid (duty solenoid c) may sticking. I've seen this a couple of times, once in one of my cars. Take it to a Subaru dealership (as you always should, they have the info and the tools required to test it) and ask them to do a pressure check for the transfer circuit. That is how I diagnosed mine. You can also turn the ignition to on and listen for the solenoid, but this is very hard to do if you don't know what it is supposed to sound like.