Thanks for the tip... I'll give #2 a try tomorrow. Too late to go to the hardware store tonight. I don't think I can fit both nuts on the front side with the starter still in place. 
May well just be the solenoid... Geometry of the starter doesn't lend itself to a screwdriver start. Planning to try a rebuild once the new starter comes in.
BTW, darn that starter looks clean. Are you sure it's not just the solenoid? Either way you can probably rebuild it yourself on the bench pretty easily once your new on is installed. Then you'll have a ready-2-go back-up. I got a starter like that on Ebay about 4 years ago for $79 shipped. Installed it. Rebuilt my OEM expecting the Chinese starter would get me through one season- and guess what? That Chinese knock-off is still cranking like new.
May well just be the solenoid... Geometry of the starter doesn't lend itself to a screwdriver start. Planning to try a rebuild once the new starter comes in.