Ok I need some help. I've posted about this before and I thought I could manage the issue, but it keeps getting worse. Here's what happens....I'll begin the day just fine and start printing meshes (this happens with all my prints now). But as the day goes on, it seems like either the printer is changing the offset by itself, or when the bed homes, it doesn't always home the same way (z-axis) every time. Sometimes it's 0.2mm off, sometimes it's 1mm off, sometimes it's 0.5mm off (these offsets are always positive, from the actual z-offset point to the bed). It has no discernible pattern whatsoever. I've moved my homing position into the middle of the bed so there's no problem with edges. I've replaced my IR sensor, I've cleaned my IR sensor(s), nothing seems to help it out. When I do my z-offset AND when I home the bed before every print, I do it the exact same way, with the exact same bed and hotend temps. I thought maybe it was because I had glue stick, or hairspray on the bed (I have a glass bed) that was interfering with the IR sensor, so I do everything on a pristine, clean glass bed every time. I've cleaned and greased the z-screw, I've cleaned and greased all of the X/Y, and Z rods/bearings; there are no more variables to consider. Sometimes what might help is reflashing the firmware and starting from scratch, or doing an M502, M500 to clear the z-offset and then do that again. But no matter what I do this keeps happening. What's weird is that I guarantee when I come in tomorrow morning it will do just fine, maybe even for 2 or 3 mesh prints, then it will start offsetting again. I can never, ever just start a print and let it go and feel confident it will do what it's supposed to do. Even a 0.2mm offset ruins the entire print. I always have to visually check that it is homing properly by issuing a G28, then a G1 Z0. 2 hours ago it was fine, 1 hour ago it was offset by maybe 0.3mm, and just a few minutes ago it was offset about 1.2 mm. Like I said, it's a crap shoot and it's getting worse. To the point that I can't even calibrate my mesh anymore. Has anyone had this problem, or does anyone know of something I can try? I'm seriously desperate because I've got prints piling up and no way of completing them. Somebody please, please help. My sanity is at stake here...............what sanity I have left anyway.