1998 Subaru Legacy Question: TCC solenoid

car has 152,000 miles, rebuilt trans (10 months ago) has 20,000. use on a paper route, so rough treatment. Got a P0740 code. Son has replaced a TCC solenoid on a couple of other cars, but never a Subaru. Does valve body have to be removed to replace solenoid? He's worried about bearings inside the valve body. Could he mess something up by removing it? Any special care have to be taken while handling it? He would like a diagram but all I can find is downloads for a whole manual. Is there something else we should check before replacing the TCC solenoid? Basically anything you can tell me would be helpful. Thanks so much!