Samsung ML-2251NP - Manual (Page 109)

M AINTAINING Y OUR PRINTER
5.4
3 Gently shake the toner cartridge from side to side five or six
times to redistribute the toner.
N OTE : If toner gets on your clothing, wipe it off with a dry cloth
and wash clothing in cold water. Hot water sets toner into fabric.
4 Reinsert the toner cartridge into the printer. Ensure that the
toner cartridge snaps into place.
5 Close the front cover. Make sure that the cover is securely
closed. If it is not firmly closed, printing errors may occur
when you print.