1. Check the probe assembly mechanics: Loose nuts, bolts, springs, bent or worn guide rods, and bearings. Check the encoder gear, rack, etc. Make sure both probe tips contact the web of the material the same.

2. Check the alignment of the encoder gear and the gear rack through entire length of travel for the probes. 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. 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 probes fully extend and retract. If they do not, the machine may initialize the probes at the wrong position, causing incorrect measurement. Often dirt, grease, or punch slugs will keep the probes from fully extending or retracting.

4. Check that the probes are extending and retracting at the correct air pressure. There is an in-line air pressure regulator and 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 probes, there is probably a mechanical problem.

5. Check that the probes are extending and retracting at the correct speed. There are flow controls in the extend and retract air lines for the air cylinder. They are either part of the air valve or on the extend and retract ports of the air cylinder. The probes should extend and retract at a smooth easy speed. If they move too fast, the banging of the probes 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 and cause it to mechanically fail. If they extends too slowly, the probes may not stay in contact with the material as a part is being processed. During a part run, the probe tips must stay in contact with the material all the time for accurate measurement.

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

7. Enter the DIAGNOSTICS for the flange unit that is being checked. In the middle of the computer screen, the encoder count is displayed under the heading COUNTER. With the probes retracted all the way, note the encoder count number that is displayed. Extend the probes using the specified function key. The encoder count number will count up or count down depending on the individual machine (Count direction is shown on drawing # XXX-904A and # XXX-904B). When they are fully extended, note the encoder count number that is now displayed. As the probes are extended and retracted, the encoder should count up and down 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 an encoder on one of the other punch units to determine if the encoder or the cable is bad.