After many cuts the rubber roller may become dusty and slippery.  When this occurs, the CoLibri machine can't separate the plastic waste. Place the machine vertically. Get rubbing alcohol, a cloth and a paper towel.Using the alcohol-moistened cloth, wipe the rubber roller along the surface.Then, vigorously rub the roller with the paper towel so that paper dust is deposited to ensure a greater friction and a better grip. CAUTION:Make sure the to switch off the unit, turning off the main switch, and disconnect the power cable.