tram lines

Hi all,
Long time owner and lurker on the forum. I'm noticing more and more this issue - tram lines around text. Weirdly, it only happens around the text and not an open field. I take it this is a spindle/router alignment issue - not 90° in one direction? This is being cut on Duna HDU, 1/8" bit at about 100ips. I'm taking it slow because of the detail in other areas and not to stress the bit too much.
Ideas?
Thanks, Rick
http://www.talkshopbot.com/forum/att...id=34544&stc=1