Glasses/tumblers move/walk left or right while engaving using Rotary Roller RR2

I’ve just started using the Rotary Roller RR2 with Alpha Mk 2 20W. I am having an issue where I am trying to engrave a highball glass and no matter what I try the glass “walks” to the right resulting in text etc not engraving horizontally and shapes like circles being distorted. The RR2 is level and parallel to the X axis, I have tried moving the rollers closer together (helped a bit but did not eliminate the issue), and adding weight to the glass. Any advice would be much appreciated.