I made a quick jig today to flatten the casting surface on these 273 rockers for locking adjuster nuts. As you can see the original castings are way off Measured the rocker shaft and it was .87”. It just so happens a craftsman 5/8” deep socket is also .87”. Well I drilled a 7/8 in hole in some straight scraps and the socket fit snug. Then I squared everything up to the disc sander. I screwed in the adjuster nut and then flipped the locking nut. I referenced it to the flat surface of the sanding disc I set up a couple of fences to keep things squared up. Went through all 16 rockers in about 20 minutes carefully checking each locking nut. Pretty happy with this set up.