Lost zero after 10 cuts

Hi guys, I have situation - after last maintenence (cleaned and greased) my Alt Mill start moved 0 point to front by 2mm after 30 min of work, after 1 hour it’s change 5-6mm. I do 3 cuts in one panel 24"x48" and use same G-code all of time, after 10 panels machine zero move 2 mm to front and at gSender shows 0 at screen , can anyone have idea why this possible happen? (I checked g-code, all is good)

@DanBtek I can’t say I fully understand what you are explaining. But assuming you power cycled the SLB after your maintenance, did you re-home? Re-homing is required after a power cycle and should preserve the zeros to 0.01mm accuracy according to the tests I made in the past.

Thanks for answer, I will check when start next order for my customer but this what you say make sense. Thanks again.