Possible causes:
Zero point sensor is faulty, out of adjustment or improperly connected. It could be that the table locking pin is jammed or skims sometimes.

Solutions:
1- Check the locking pin. Refer to the protocol A-IND-029 to inspect the componants, lubricate or adjust it if needed.

2- Check the connections, be sure that the good wire is connected and fully screwed to the zero sensor (wire with green ty-rap on connector).

3- Check the adjustment of the zero point sensor (adjusted at 1/8″ between main table gear and sensor tip)

4- Check the sensor, he should lit up when detecting metal and off when no metal detected. Replace the zero point sensor if defect.