I spent some hours today trying various diagnosis methods.
I tried jumping the power straight from the battery to the solenoid. Still nothing. I took off the wires connecting to the starter and cleaned and tested as many as I could. All seem fine. On the starter there are only two connections. The power from the battery/to the alt, and a yellow/green wire. What is this wire and where does it go. I traced it but it disappears in a maze of harnesses. The only response I received from the starter was after on of my "whacking" sessions. I took a crowbar and started tapping the solenoid to elicit a response. I was alone so I couldnt do it while someone else cranked but I did get the starter to click a few times when key turned to start. Looks like I am pulling the starter out soon. Is this a difficult process in the volvo? It looks to be very accessible from the underside. How many bolts? Any other concerns?

The starter in my 83 BMW would randomly leave me stranded until I had it rebuilt last summer. About $60 US. Rebuild included new brushes, contacts and solenoid. No problems since.