to easy adjust the z-level height use this holder and a micrometre (MITUTOYO, Serie 148, 0.01mm).
print both parts.
mount holder with a M4 20mm Screw.
mount switch in this way:
Z-Motor Block hole> Long screw (you can use the existing or a 35mm)> Switch Holder> Washer > M3 Nut > toothed washer > switch > washer > M3 Nut.
to adjust the zero point be sure to have your bed level.
check that your nozzle is clean.
manualy move the nozzle to the bed until it hits, turn back a little bit.
adjust micrometre to zero until your switch clicks.
try autohoming (be sure to not drive into the table)
your nozzle should not move into the table.
to print adjust height to desired distance!