Just a comment on the process and getting the top bolt out of the starter.
I ended up using a 3" extension on the socket, then a universal, then a 16" extension. This gave me enough clearance to swing the ratchet meaningfully (more than two clicks per turn). I did not remove the exhaust bracket as suggested by the OP. I found I had enough clearance to get both bolts out with the bracket in place.
After loosening the bolt, by sitting with the brake rotor in my lap, I was able to get one hand under the starter and one hand on the 3" extension and turn it the rest of the way out by hand.
After the bolts came out, I was able to turn the starter so the pinion was pointing forward, then bring the starter back by the exhaust collector, then swing the brake lines (previously unbolted) aside and wiggle the starter out through the wheel well. I am not a fan of fiddly in-frame work. As you bring the starter out, the front of the starter will be pointing back over your left shoulder (if you are sitting in the wheel well) and the solenoid box will be at about 2:00 to clear the exhaust flange and avoid the brake lines. I pushed the brake lines to the left to start the process and then just before bringing the starter out, pushed the brake lines as far to the right as they would go without feeling as though I was damaging anything. At this point the starter slid right on out.
I'll try to get some pics on the re-install.
After looking at the contacts, one is severely worn, the other not so much. Of more concern at this point is the cable going into the starter body. The rubber boot is crumbling and in fact, fell apart as I handled the starter. Although the underlying braided cable looks connected, there is a lot of tarnish on it. I am wondering if it is worth replacing just to avoid the headache down the road.
Pics as promised
going in over the frame rail, don't cut the boot on the body flange
rotated forward a bit and going past the brake lines
turning around for installation of bolts
almost installation position