Possible Bent Shaft?

Hello everyone


We've been having a problem for some time now with one of our servo motors not riding along the rack "nicely".
I won't go into all the details right now as I think I may have found the problem and was hoping for some feedback on my findings.


Attached is a photo of the rack.
As you can see there is an almost crescent like shape or partial circle shape on the rack.
This shape re-occurs at regular intervals along the rack.


I thought it might be how the motor was mounted to the machine...perhaps it was crooked....but if that was the case it would have a continuous line or pattern all the way along the rack.
Then I thought it might be the rack itself was out of wack...but if that was the case the patterns would not be exactly the same at regular intervals.


My final thought is this....the shaft that connects the motor to the gear (the gear that rides along the rack)...the shaft is bent just slightly.
I'm thinking this would cause the gear to connect perfectly with the rack, then at an angle, then perfectly, then at an angle....thus causing the pattern we see in the photo.


So I'm wondering...do you think I'm right or is there something else I'm missing?


Any feedback wound be great.
Thanks
Ryan