GSM Calibration; Z-axis not touching down to pickup calibration card.

We have two GSM machines (4-spindle, single beam) and had a camera fail on one machine. We decided to clean and calibrate the cameras on both machines. One machine we had no problems and all is working properly. The other machine will not pick up the calibration card. The spindle stops about 50-100 mils short of the card instead of going down until the touch-down sensor detects contact.

I verified the spindles height is within tolerance with the spindle height fixture and the touch down sensors are working and adjusted properly. As a test, I stacked another calibration card under the correct one to raise it. The spindle was able to reach and perform ULC calibration, but during head calibration the head was unable to pickup the card again when it placed it on the vacuum post.

I found document 48653501 which describes "spindle height calibration" but I am unsure if this is the correct procedure, and it is not available on my machine (ups 3.2) through the "Task Selection" menu. This procedure also mentions mounting the "calibration nozzles" which I am not sure if these are the 360 nozzles described in document 48653201 which has a chart showing which nozzles should be used for calibration.

The PEC camera on this machine also appears to be out of focus so it may need to be adjusted.

Does anyone have any idea why the machine will not lower the spindles enough to reach the card in the calibration fixture or on the vacuum post? I tried setting the calibration parameters to a specific Z-axis location as noted with the manual controls and touch-down sensor activation but this made no difference.

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