Switch of the printer first.
Open the barcode printer by pulling two side levers towards the front of the printer.
Black coloured printer roller will be visible as shown in image.
Swipe the roller head with a piece of tissue roll soaked in 70% isopropyl alcohol solution.
Swipe only once in one direction,if another attempt is required than use new piece of tissue roll soaked in 70% isopropyl alcohol solution.
Close the printer by pressing the coverlock inside as shown in image and tick sound will be heard when printer close.