E9713, E5013,E49
Typically errors in the sensor gate are caused by debris, dust, or other obstructions in the width/height sensor gate areas. A soft microfiber cloth slightly damp (Water Only) should be used on all window surfaces. The removable width cover is the most likely place to begin. All windows should be wiped at the beginning of the day or shift to ensure consistent operation.
The window underneath the cover below the belt gap will need occasional cleaning. A long handle feather duster, or something of that nature will need to be carefully used to clean that lower window. This should typically be done once a month under reasonably clean conditions. More often if needed.