Qt-15 backlash

Hello all, I have a question regaurding backlash in a Mazak QT-15. Is there a way to adjust the backlash more specifically on the Z axis? I never have had a problem with this machine repeating and last night my operator crashed the machine:angry:, I got all of the tools reset and everything seems to be fine on the x axis and will repeat cutting diameters within a thou at best, but must have done something to the Z because now all of the sudden it is varying .010 in part thickness while parting off. I put an mag base indicator on the spindle and am measuring .020 in backlash:(. What could have happened mechanically to cause this? Before the crash, the parts were coming out +/- .0015

Please Help:cryin:

Nick