I ran the procedure exactly as per carbide 3d article on homing (CM3).
When I switch on the Info screen comes up and shows.Machine Idle no file loaded with toolpath extents for x, y & z as 0.000 Not Homed.
Next I switch to MIDI tab which shows: X:241.20. Y:266.50 Z:0. I send $22=1
I then open Settings which shows settings on lines 1005= True 1006= 420, 1007=420(I changed 420 to 430 manually).
I switch back to MIDI screen and send $h and values change to X: 236.20, Y:261.50, Z:-5.00
It seems the switches are backing off the required 5mm but X & Y are starting from other than zero but I don’t know why. If they started at zero on first MIDI screen it would all be OK and final values all at -5.00 as expected