The issue was found before I even got the belts on. I will check it out tomorrow. I suspect the problem is caused by one of the middle end pieces. One of the x axis ones was done on a totally different printer with and it was super tight getting it on the rail even with everything loose. Unfortunately the printer that I used to make the other ones that worked great is unavailable until probably this weekend. Hopefully it is something related to that or something being to tight. I have to take the gantry rails out anyway to replace the corner block locks. Idk what happened, but I came back to it today and they were all cracked (though they weren’t the other day). Im going to put some sort of spacer in there to make sure I can’t over tighten them this time.
Side note, I switched to the 11mm z nut holder thing and man was that a pain to get the bottom right screw in without disassembling the center assembly. I ended up hot gluing the nut to a screwdriver and held it in place until it was threaded on enough to remove the screwdriver and glue. Would have been easier if it was off the rails, but maybe that could be something to consider in the possible second version machine. Or just naming the 11mm one as the standard… I noticed a few other people had the same z issue I did and had to switch to the 11mm.