Thanks to all who responded with suggestions for this perplexing problem. I discovered my spindle is not quite perpendicular even though the frame, waste board, side rails and gantry are all well within an acceptable tolerance. I did mic the mounting holes for the router mounting bracket on the Z Axis plate (to the edge of that plate) and noted that they do not match by about .005". Is that enough to create the effect you see in my photo?
The only thing I can think to do is enlarge the router mounting holes on the Z plate slightly, which would allow me to tweak the bracket in the right direction. Does this make sense or is there a better approach?
Last, a finishing pass intrigues me… I am new to CNC operations, do you have a link to this process?