It seems a Z axis issue is more likely considering the periodic nature of the banding, but dealing with that might be pretty difficult if it can’t be resolved by checking for loose set screws in the coupler (one to the motor, one to threaded rod). I did notice two things about the pieces though, and it might be worth trying some other easy things first:
It could just be the lighting, but it looks like the face of the objects show less banding than the sides. Perhaps you have a loose belt or set screw on the X or Y axis. This shows how to tighten the belt: https://ohai-kit.alephobjects.com/project/784ea964-3bfc-4714-821b-1970ab6f843d/ The manual gives much the same info: http://download.lulzbot.com/Mini/1.0/documentation/manual/LulzBot_Mini_manual.pdf It doesn’t say how tight to make the belts though, just to not over tighten them. I have been wondering about the correct tightness myself.
If you look at the bottom of each piece, the part that touches the buildplate, you see that there is some extra extrusion around the entire perimeter of the pieces you printed, and not on the factory piece. If it is over extrusion, measuring the filament diameter with calipers and adjusting that number might help. You can also adjust the flow rate. You have to do this in expert settings. There’s also the initial layer width option you might want to check – the default is 125% but I would think that would affect only the initial layer being a little over extruded. Assuming the factory piece was printed with this 125% first layer, you are now getting a lot more filament coming out than they did at the factory, probably over the entire print.
Also your build plate might have loosened. Do the edges perpendicular to the X axis wiggle up and down? Mine did after a while, just remove the print surface and tighten up the screws underneath that attach the plate to the carriage. I don’t think this would make the regular banding you see, I think it would look more random, but it’s worth checking because it takes only a second.