The wheels keep spinning every couple second after the machine powers on, and indicates the “hopper sensor error” or “main motor error”, how to fix it?

If the wheels in the hopper are consistently spinning after the machine powers on, and then stops with the “hopper sensor error” or “main motor error”, the hopper sensor is too sensitive.

Figure 2-10 Use Marker Pen to Decrease the Sensitivity of Hopper Sensor

Please use the marker pen to paint a little on the hopper sensor as shown in the above figure.