Ugh…I suspect all these problems are mostly or entirely user error!
I went through a bunch of the these suggestions, short of completely dissembling the middle section, and was still coming out with the same measurements (about a 1/4″ off with the steppers relaxed.) However, just as I was getting frustrated, I figured I’d see if I could manually park the tool as you originally suggested. I plugged everything in, powered it up, and low and behold, when I manually moved the tool it would stay where I set it! Aha! Then, just as I was getting it close to square, the steppers stopped holding again. I think the whole problem is the steppers disengaging while I’m trying to set the gantry square for the cuts.
Here’s what I’m doing.
1. I plug in my laptop to the board, connect Repetier Host.
2. I move the tool with the manual controls in RH. Everything is working.
3. I try to set the tool square to the corners. The steppers are engaged for a minute or two, then disengage. Is that normal behavior? I feel like I’m probably missing something really simple here.