Let me check again...
* The stepper motor works smoothly when in hand.. unmounted from the axis.
* The mechanism moves smoothly when pushed by hand without the motor mounted.
* The axis jerks violently when run with motor mounted..
Do a small test... with the motor unmounted.. set the motor to a slow speed movement. Use your hand to push the axis around. Does your manual movement of the axis cause the motor to move in any jerking motion? I think that all this information tells me that there are some loose wires at the end of the axis where the motor connects to some cables..
Ray Scott
www.scottware.net
3503 Carol Ann Lane
Middletown, OH 45044