BCH6

I'm having this problem with a 2002 Outback Wagon LL Bean H6. Terminals are reasonably clean, power to accessories stays good after attempting to start car. Loud single click each time you turn the ignition. Usually starts after a few tries sometimes as many as 10-20. Today for the first time my wife couldn't get it to start. Car has been good to me, but has too much wrong with it to sink a lot of money into it. Hoping I can fix it myself for short money. Reading through this post it sounds like I need to replace the Solenoid contacts. Anything I need to know specific to the H6 engine? Is the starter a sealed unit? Can I replace just the contacts? Any place that walks through the steps? What do I have to remove to get to the starter? Will a starter on the shelf at a big box store work fine or do I need a suburu part? Thanks in advance for your help