Bad stepper ????

[Gambo]

Or the little plug in stepper driver module on the main board. Swap the Z axis module and extruder modules over to see if the extruder works

[Bruce19]

I have swapped mainboard connectors around and the extruder connector is on say for instance the Y axis, the "extruder stepper" motor works fine. When I take Y axis mainboard PLUG and place in extruder mainboard not even a shaft movement happens. I've done about 6 different combinations to troubleshoot what's at issue. And determined the extruder stepper motor is goog, The wire from mainboard to ext. stepper is good. But when I connect a known good wire with another axis stepper, absolutely NOTHING happens. All my stepper motors are good.

So I've determined its something on mainboard. The printer is over two years old.