Problem with the Carriage Encoder Sensor readings
Try the following:
1. Check that the encoder sensor is correctly connected to the Carriage PCA.
2. Make sure the Encoder Strip is not broken or damaged. If necessary, replace it.
3. Make sure that the Encoder Strip is clean. If it is dirty, clean it, paying special attention to the area near the Service Station.
4. Clean the Encoder Sensor.
5. Replace the Encoder Sensor.
6. Replace the Carriage PCA.
7. Replace the Trailing Cables.