So I'm printing this F1 car at the moment. I have replaced the z-axis parts with the new ones and printed out the nose cone and then the front section. Last night I printed out the main body section and the z-banding has returned. The print profile is exactly the same, same filament. The only thing, previously I was set at an incorrect steps per mm, however, the prints were still fine. I re-calibrated my steps per mm last night and printed a test cube. Steps per mm went from ~270 to 315 and I have set the extrusion multiplier to 0.94. The test cube at 1 perimeter, 1 top and bottom, 100% infill came out perfectly sized, with no banding and no gaps top and bottom. In the image below the part of concern is on the right. Is this an (over) extrusion problem and not something mechanical? If so what should I do to resolve?