Cubiscan 200SQ E20-21 to E34-35 object is not detected by photo sensor(s). E5015 to E5022 Photo sensors blocked or misaligned.
On the 200SQ machine, the photo sensors are located along the edges of the green conveyor belts. The sensors themselves are protected behind small plastic windows that are recessed into the edge panel assemblies. To access them for cleaning, the top plates along the edges of the belt will need to be removed. A number 2 Phillips screwdriver will be required.
On very short items (Height), Errors E20-21 through E34-35 will be common errors as the item is too short to trigger the Photo Sensors properly. Taller boxes, bags, etc. should measure just fine. If errors E5015 through E5022 are displayed, this would indicate that the sensor(s) are dirty, blocked by debris, or misaligned somehow. Use the System Info>Photo Sensor Page (No login needed) or the Device Testing>Photo Sensor screen (Login Required) as displayed below to determine which sensor(s) need attention. 
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Once the issues have been cleared, and all sensors turn on and off as they should when blocked and unblocked, press the Exit Key to return to the main operations screen. The system should now run and measure without issue.