Hello Roxy,
Ive been lurker here and just wanted to say thanks for the huge amount of help you've offered here.

I am just trying to use my z probe for the first time, so I thought I would start out easy by trying the M48, but it doesn't work.

First, I have a delta with a probe that is placed by hand (which means it doesn't need to be engaged or retracted, so just for now, I've inserted a return at the top of those routines) and the switch trigggers when at 18.21mm above the zero location (as determined by the paper test - it prints fairly well at this point.)

When I execute a M48 v3 the probe is lowered to Z_RAISE_BEFORE_HOMING, but then it just stays there, printing out a report with all the same values. Debug statements Ive inserted show the run_z_probe() getting repeatedly called, but nothing moves.

The m119 appears to work fine - the probe (hooked into zmin) is OPEN normally, and TRIGGERED when the switch is closed.

Any ideas?