I have a couple of these in my shop and there's no way to adjust the half nuts without separating the apron from the carriage. What I do is bring the whole assembly to the very end of the lathe, then take my bolts out there. if you have a hoist, eyebolts in the carriage makes it easy. If you don't have a hoist, this job is more difficult. Above all, make sure you properly hold the apron up with some boards and make SURE you support your lead screw. I made up a support out of 2x4's that wedge in between the lead screw and bar. Once separated, run the apron off the end just far enough to get to the half nuts. There is an adjustment for the half nuts and since you're dragging against the lead screw, just open the gap adjustment a hair till you're not touching. This will eat up the half nut quick and i can tell you from experience that making a new set is not fun. By the way, if you make some, i've been making them from silicon bronze and they hold up well in all of my machines and we thread on all of them everyday.