These were fairly loose and the cracks were not there until over a week later. The tops of the bolts were more flush than the bottoms which had a fairly decent sized gap. I have the nuts just tight enough to lock with the nylon. While moving the axis back and forth, a few nuts wiggled loose and fell out. I may just try some lock tite. Maybe with the bot heads being flush made it too tight.
I do not have those gaps on the middle Z assembly. Should those be that loose as well?