Autoleveller

As mentioned in the post, when the probe [mill] touches the PCB surface, the digitize input in mach3 lights up, and it works a 100% of the time, so doesn't seem to be related to physical hardware.

I have a 6040 cnc using mach3, and I'm running into a weird issue. When I start probing all seems good for the first couple touches, but suddenly it stops detecting and pushes into the board to the maximum probe height, if I let it continue it eventually goes back to probing normally but the final r...