So it happens more frequently now. But the Zero Z function crashes into the Puck and tries to continue in -Z direction. I have checked the Cable and the screw and the little connector. it happens about 1 in 20. Enough to make me worry every time. When it does that it really messes with all to XYZ positions. Which gets expensive.
I'll open the panel and check those connections after lunch. I have the machine OFF right now and resting in X=0 Y=0. I'll try again after lunch. Maybe with a 1" block of foam under the puck to lessen the beating when it tries to continue down.
You could have a broken wire on the puck. Flexing could break the connection. Put a meter on the cable from the puck surface to the end of the puck cable and see what happens when you wiggle it around. Same thing with the puck female connector. Could also be a bad connection in the puck. As delivered there is not a good strain relief on the puck.
If you have an analog meter (not digital), it works great for checking these types of problems. It's easier watching for a needle to dip than it is watching a digital display change. I've kept my old one just for this type of problem.
You can also use the continuity tester function of a reasonably quality digital multi-meter. They typically will beep when a circuit is closed. Connect the probes to the touch pad and to where the wiring lands in the control enclosure and listen for the constant "beeeep" to be interrupted or crackle as you wiggle and move wires and connections.