I just took a look at my tube. Yours appears to be normal. The spiral portion of the tube has an open end about 1/2 a turn after the small tube that connects the spiral to the main tube.
The door interlocks are most likely based on magnetic sensors, because the manual warns that magnets can accidentally create false indications of door status. There are a pair of magnets that are brought close together when the front tray door is closed. I’d check too see if there is something causing them to stay too far apart. I’ve only had a door open error one and it was because the magnets were slightly separated.