Broken shaft on NEMA 23!

Yesterday I was doing a basic surfacing operation when I noticed the gantry not moving evenly. One side moved smoothly and the other jumped. I had a similar issue a long time ago and traced it to a loose wire in the control box. With that in mind I went to the box and everything check out okay at first glance. I went back to the table, looking at the motors, I see on the ground the pinion laying there! The shaft had sheared off.
So no I am looking for a replacement stepper motor. What I currently have is the NEMA KL23H286-20-8B. I order two (one for back up) on eBay from automationrolls. The next day I get a notice from them that the motor is not in stock even though they list more than ten available(?). They offered to send the NEMA kl23h2100-30-4b or the 35-4b, he said that either one will work just fine.
My concern is I know very little about the mechanics for these machines and do not want to mess it up by miss matching motors. Any advise on if these would work with the existing motors and the existing drivers, power supply ect.? Please let me know if you have any suggestions or direction I should take.
I have searched around a bit and can not seem to locate this original motor. The ones I do find are sold by the same outfit under a different name, all coming down to automation technology....
Thanks for the help,
rockaukum

Lots of looks but no advice. I finally found a replacement the same size and all. Got the new one installed and wired up.
New question....
Being ever inquisitive, I decided to take the broken Nema 23 apart to see what is inside. As I got it apart, I see that it is symmetrical. I rotated the motor portion so the shaft out the back is now out the front (side with mounting plate). Any ideas if this will work as before? Will it be out of balance due to the broken shaft?
I hope to remote wire it up and give it a go. If it works, I now have a backup motor, if it does not work, I got another paper weight!
rockaukum

you got a paper weight , stepper motors don't like to be taken apart

I haven't taken a stepper apart but would expect that if its a DC stepper and goes back together you would have to reverse the polarity of the connection to get the correct rotation.Whatever the outcome,posting the result here would be useful for anybody who has the same problem in the future.

Hi,

It should work with less torque. This is what I have heard. The magnetic field collapses when you takes the rotor out and it has to be re-established when putting in. The magnetic field is reestablished in a machine. I only have heard of this and have no personal experience. But this is why they say not to take the stepper apart. but try and let us know.

Regarding balancing, i do lot of rotor balancing. if the shaft is broken flat, no worry it won't cause any issue. if not then grind it flat like before. Even if you don't given the mass of shaft and its distance from the center and the speed at which they rotate, balancing won't come into picture.

I've taken apart a number of steppers for curiosity reasons and they are never the same afterwards . If the motor turns then it will have a fraction of the torque it had in the past .

I recently had a stepper crap out on one of my mills .When I pulled the motor off the mill I noticed the bolts had come lose which made the casing lose from the caps . I hoped that tightening the bolts would be enough to make it good again but it's finished and couldn't even lift the head on the mill

I took my X & Y steppers apart before I knew that I shouldn't. I did this because they were dual shaft and I wanted to cut the tail shaft off. I only had each one apart for a about three minutes. I have never had any issues with either. They have been running on a Sieg X3 mill. Not endorsing taking them apart just relaying my experience.