The left-side case bolt threads into this boss on the right case across the front cylinder base. It's already been heli-coiled down in the hole farther. The threads look solid and good. I'll probably leave (as is) since trying to fix it may create a mess? The case needs clearance for the connecting rod anyway. (that's why it's so thin in the first place) I'll just be careful with the case bolt tension on reassembly. I may smear it with some red glyptal or The Right Stuff . . . .