Avision AV1860 (DL-1101S/DL-1103S) - Manual (Page 106)

8-4
8.3 Cleaning the Calibration Area
1. Press the Paper Jam Clearing button. Open the front door
to the left.
2. Wet a clean cloth with some isopropyl alcohol. (95%)
3. Wipe the glass and the white area as illustrated below by
moving the swab from side to side to rid the dust or dirt.
Glass