Today, I learned why my probe seemed to be inconsistent in setting zero. The screw holding the wire to the magnet had come loose, so contact was a bit erratic. A quick tightening and all is well again. (Of course I destroyed the plastic cover tightening the screw, but I can live without it.)
Ah, good idea on inspecting it. I’ll have to keep this in mind into the future if someone is having similar issues. Great catch @gwilki
here is a better design of the magnet cover that won’t come loose.
Looks very good, Philip. Since I’m a hobbyist woodworker, I made my new cover out of wood.