Misaligned or out of parallel corrugator rolls can result in medium fracture, leaning flutes, and hi-lows. It can also reduce the life of corrugator rolls and the drive motor. The simplest method of checking the parallel of corrugator rolls is to use two copy no carbon required or NCR paper. When fed through the corrugating rolls, the flute tips leave their impressions on the NCR paper where contact occurs as depicted in figs. 1 and 2.