Ridges and stepping in my prints I'm having a problem where every few layers seems to be offset slightly, creating a stepping effect. The images below should be smooth along the sides, but having this ridge type effect. My question is how do I calibrate the printer to print smoothly? 

I’m using a Hictop Prusa I3. I’ve recently installed an updated version of Marlin and have been tinkering with the configuration to make it match as close to the original config that was originally installed.

Printer: Prusa I3 (Hictop)

Marlin: 1.1.9

Filament: 1.75 PLA

Slicer: Ultimaker Cura

Layer height: .16&nbsp;mm

Extruder: 190&nbsp;&deg;C

Bed: 60&nbsp;&deg;C

Speed: 30&nbsp;mm/s

Line width: 0.8&nbsp;mm

Cooling fan: 30%

Below are a few examples of what I mean by ridges and stepping
From the picture, this doesn't look like an X or Y axis problem.  I wonder if it is a problem with the Z-axis positioning?
I don't have any specific suggestions, but I would start by, with the printer off and cold, manually turning the Z-axis motor(s) to assure that the movements are smooth and without any binding.  If the movement is smooth, then with the printer powered on, try some Z-axis movements, up and down, both listening and feeling for excessive vibration or jerkiness.
What may be happening is that the Z movement is binding for several layers and causing the flexure in the Z-axis to bend upward, permitting some plastic to extrude but forcing it into a wide bulge.  When the Z axis finally snaps upward, the build layer is too far below the nozzle, so the plastic does not bulge outward and necks down until it builds a base again.  This repeats.
It could be an electrical problem with the Z-axis drive rather than a mechanical sticking or interference, but you will feel that, too, by doing slow Z-axis movements and watching carefully, listening for irregularity, and feeling for any jerk or stutter.