@bvw; personally I haven't yet printed at 70xy, but that shouldn't matter for this issue. Can you explain a bit more what is happening? That is, you click Create, vat moves, table comes down, exposure happens, then the x motor is unable to move the vat? or is there something else going on...
I'm in India where it's kind of late, but I'm up anyway and thought to help advance the solution of your issue by getting this clarification out for evening time in Europe and daytime in the US.
The only thing I can think of, if this scenario I'm inferring happened to me, would be to kill the job by pulling the usb cord so the x motor doesn't get damaged, and the z components are not damaged. Then I'd take out the Build Table thumbscrew, plug in again, raise the arm, take the vat and table out and try to separate the table from pdms with a spatula or something. I'd look to see if there was resin between the table and the pdms.
You might have a table calibration that's too tight to the pdms, you might have not enough resin in the vat, ummm.. that's all I can think of now. Looking forward to additional ideas.
ZLab3d, printing with B9Creator 1.1 & 1.2 since 2013