1. Check the probe assembly mechanics: Loose nuts, bolts, springs, bent or worn guide rods, and bearings. Check the encoder gear, gear rack, etc.

2. Check the alignment of the encoder gear and the gear rack through entire length of probe travel. There should be a little slack (clearance) between the gear and the gear rack. The gear on the encoder should be able to turn slightly (very slightly). If, at one end there is slack and the other end there is not (tight), chances are that the shaft of the encoder is being side loaded. This will cause the bearing in the encoder to fail. If there is too much slack, the measurements will be inconsistent and inaccurate. Any mechanical wear or movement in the probe assembly will cause inaccurate measurements.

3. Check that the probe fully extends and retracts. If it does not, the machine will initialize the probe at the wrong position, causing incorrect measurement. Often dirt, grease, or punch slugs will keep the probe from fully extending or retracting.

4. Check that the probe is extending and retracting at the correct air pressure. There is an in-line air pressure regulator with a gauge before the air valve for the probe extend/retract air cylinder. When the probe assembly is mechanically sound, 30-40 psi is the appropriate air pressure. If more air pressure is needed to extend or retract the probe, there is probably a mechanical problem.

5. Check that the probe is extending and retracting at the correct speed. There are flow controls in the extend and the retract air lines for the air cylinder. They are either part of the air valve or are in ports of the air cylinder. The probe should extend and retract at a smooth steady speed. If it moves too fast, the banging of the probe at the end of the travel or against the material will loosen, strip, and/or break the nuts, bolts, and bearings on the probe assembly. If it extends too slowly, the probe may not stay in contact with the material as a part is being processed. During a part run, the probe tip must stay in contact with the material all the time for accurate gauge measurement.

6. Check the encoder, encoder cable, connector, shield connection in console, & wire connections in console.

7. Enter the DIAGNOSTICS for the unit that is being checked. In the middle of the computer screen, the encoder count is displayed under the heading COUNTER. With the probe retracted all the way, note the encoder count number that is displayed. Extend the probe using the specified function key. The encoder count number will count down. When it is fully extended, note the encoder count number that is now displayed. As the probe is extended and retracted, the encoder will count down and up to the same numbers every time. The encoder count numbers may vary by one or two counts due to the slack between the gear and gear rack. If there is more variance, see step B. If the number gradually increases or decreases, or not changing at all, the encoder or the cable is bad. Swap the encoder in question with the encoder on the other punch unit to determine if the encoder or the cable is bad.