That crinkle crisp effect (with the ridges at low X becoming valleys at high X, and vice versa) is a sign of backlash in the motion system. I don't know the Rostock Max, but my general advice for a delta with this issue is:
Check that the carriages move smoothly up and down the towers. Lubricate them and/or adjust wheel tension if applicable. Check that there is no play in the joints Lubricate the joints Reduce the spring tension on the joints, if it is adjustable Check that the motor current isn't set much too lowHTH David