Here is an article I reposted a number of years ago. (Im glad I did, the original lost its images!). It goes pretty in depth in explaining cooling issues in CO2 lasers:
Here is an article on scan gaps that is just an interesting read, and maybe semi-related to the issues @eflyguy found:
This image (from the first article) shows the same types of banding that is occurring in the images from the other thread:
The pattern to look for in determining whether this is the issue or not, is the presence of engraving errors in direct proximity to changes in horizontal engraving load. You can see in this image where there is a large amount of distortion directly adjacent to a large change in engraving load.
Im not sure whether support will ever expand on this or how many people have experienced it, but I definitely know I did on my pre-release machine. Ive been lucky to only see this very very slightly on my forever machine, (except sometimes when I do an engrave first thing before the machine warms up).