Just to close this out completely, I got my lead screw yesterday. I hadn’t even taken the old one off yet, but when I did I could EASILY see the run-out on the section the bearing sits in. I have no idea how they machined it, but if it was on a lathe then they chucked it off-center. It is at least a millimeter out! It was also VERY snug in the delrin block. The new screw and new block combo spin WAY more freely. Installed them and it’s working like a champ. Got my first cut ever done, too:
The bottle cap is a 3D printed one I had someone else draw and I had printed. The tether is HDPE that I cut with the X-Carve. I found out the hard way that you can’t cut HDPE with a laser because it melts, so that’s mostly what prompted me to get my X-Carve finished finally. I re-use Smartwater bottles for backpacking/hiking and don’t want to drop the cap (or worse, lose the cap). After way more hours than it was worth, problem solved.
Anyway, thanks to everyone for all the help getting this far. Will move to a more appropriate category for things now. Thanks again!