David had a problem that sounds similar, which was related to tubes being out of round. Texas Primo (Upgrading a part Burly/part 525)
I can’t speak to whether the design is intended to flex to accommodate the 23.68 vs. 23.5 difference, but I wouldn’t assume that it’s broken just because the numbers don’t match up. I am inferring from the instructions that the intent is to have them very loose to start with so they can be tightened just enough to bring everything in contact without messing up the squareness that was established earlier. If it was tight to begin with then it might tweak the rails out of square and there would be no way to loosen it to square it again. That is just me reading into it and I don’t know if that is the actual design intent.