Hi ugotaccpaced, I see - so yeah that's coming from some wavy-ness in the lofted surface where it intersects the vertical extrusion. So getting rid of that would involve making the loft surface shaped flat in those spots, it sounds like you already figured this out.

It's also possible to turn on surface control points and select some points and then in the side view grab the scaling grip corner of the edit frame around them and squish them down flat, that's another way to flatten some areas of a surface.

- Michael