I wanted to continue this thread just to conclude it, as the car has been down for a few weeks while I waited for a starter from Tasca. I replaced it last night and still got no start- it turned out to be the positive cable. As soon as I replaced that it fired right up. I suppose the original starter is still good, but after 160k miles I'm fine with a new one anyway.
I was hesitant to replace it previously because it appeared to be in good condition. If my troubleshooting skills were up to snuff I suppose I could have checked it earlier and saved some downtime and hassle. Water under the bridge now.