If you jog back and forth, you should read 0V in one direction, and 5V in the other direction on the DIR pin.
You can't really measure the STEP voltage, but it should be close to 0V when it's not moving.
Are you sure you have the portts and pins assigned correctly? Sounds like a wiring or breakout board issue.
It's not normal for any drives to fail at all, ever, but it does occasionally happen.Is it a normal thing for all 4 drivers to go bad in the middle of a tool change?
That's not heavy at all. Properly sized Nema 23 motors should have no trouble moving that.some advise on a package that can drive a Heavy Duty CNC, at least NEMA 34 size motors because my gantry weighs around 75lbs with the spindle and water cooler on board the gantry.