X carve, Acme upgrade and UGS - Z axis repeatability

Having a problem on a job where my Zaxis keeps gouging parts. Already stiffened the X. Did the lock nut, longer
bolt mod on the z axis v wheels eccentric nuts ( no spacers yet…)
Feeding down slowly. Trying to cut a 46mm square, and the Y- side is cutting randomly from perfect to -.010 into the part.
Any suggestions?