Incorrect settings for colored paper can cause problems with skew and shift in the registration unit. When this happens, the machine will issue JAM 49 (Over Skew or JAM 50 (Over Shift).
The Leading Edge (LE) Shift Unit is equipped with a CIS (Contact Image Sensor) [A] that detects the reflection of the leading edge of every sheet of paper as it passes.
The luminance of the reflection is determined by the color of the paper, so it is very important that the color setting for the paper in use is correct. If the color setting is wrong, this could cause incorrect CIS readings which can cause paper jams.