Rotary axis slippage?

Hi All, I am trying to get a tapered twisted leg on my rotary axis. The STL file looks good. For some unknown reason the lines running from top to bottom will get out of wack during running the program. I can not figure out what the issue is. Any help would be greatly appreciated.

I have attached some photos that might make my issue more clear. As you can see in the image, the bottom looks good, but then…

Thanks!

Have you checked the set screw that connects the motor to the chuck?

Welcome to the forum.

Did this happen more than once? The same way?

That seems to have done the trick!
Thank you!