I had this happen on a 11.5 x 33" board while doing a carving with centerline text in the pocket, centered on the board, always under the rollers. Last line is wavy. My guess is something to do with the X axis feed. I then carved another one, different board, which came out perfectly. The only variances was the boards. There was not any error msgs to check the X axis, but I have seen some strange things since converting to the rubber rollers on the X axis. I have double checked the machine's assembly but found nothing amiss yet. This could be several things, from a software glitch not reading the board positions to the board slipping in the X axis. I will keep observing.
Greg Luckett
Great Lakes Wood Arts Co.
Saint Joseph, MI