After going back and re-reading my last post. One thing I can recommend for the auger bolt, is to use a softer grade bolt. Like a grade 2 bolt instead of the grade 5. I did that on mine when I popped the first one. The first time I popped the grade 5, it sounds like a gun going off. The time I popped the grade 2, it sound like a normal "clunk" and of course the auger stopped turning. (Don't even ask what I was doing... it was pure stupidity).
GR5 = grade 5.
Plus when mine broke, I looked at the head.
Don't get me wrong, replacing it with a grade 5 will be fine, I'm sure, but I just didn't like the sound of a grade 5 breaking to begin with. After doing the "punishment" test, I just don't feel comfortable with using a treated bolt.
My wear bar looks OK after several years of driveway abuse.