Gaps at Layer Change Location

[N5QM]

All,

I have printed some 20mm cubes and dimensionally they look great, however I am seeing small gaps at the location that a layer starts/stops.

If I set the layer change to happen in random locations it is all over the place, if I use the default value of changing in the same location, it ends up being a corner that looks "off".

I am using Slic3r for all of this and was thinking that it might be a setting dealing with retraction on layer change and have started experimenting with that. Does anybody have a suggestion on what else I might try?

Robert