Spindle Sporadically Readjusts Midcarve

I finished my X-Carve not too long ago but have failed to be able to complete even one project thus far. The issue that I keep running into is that the spindle will readjust midcarve and suddenly sabotage the entire carving apparatus. It regularly occurs at about the 20% finished mark. I’m attaching the pictures to this to give an idea of what I mean. Could someone please tell me what to do?

Thank you.

First things to address are the belt tension, and the V-Wheel eccentric nut adjustments.

Instructions can be found near the bottom of this page. X-Carve Instructions: Calibration and Maintenace

Thank you, Seth. I’ll get to work on it asap and see if this fixes the pending issue.