DL3 loses alignment

I have a unit that constantly loses alignment on a show. 2 weeks focused on a box and everyday it is exactly 1 foot to the right. Every day we move it left and update the cue, save the show, do the gig, and lamp off the rig. Next morning the units are homed and re-lamped, and like clockwork a foot off. Im the DL3 tech on the show, but I feel confident that it's not OP-Err. I think I saw this on another gig but it was so run and gun that I dismissed it. But this time it is consistently happening, and with only one unit but not it's twin.

Any ideas?