# Y axis left rail moves with a jerky motion **URL:** \ **Category:** Elite Series (Masso & Redline) (Gen 1)\ **Created:** [May 6, 2023, 4:44pm UTC](https://forum.onefinitycnc.com/t/y-axis-left-rail-moves-with-a-jerky-motion/20464 "2023-05-06T16:44:05Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![349iq2345](https://avatars.discourse-cdn.com/v4/letter/3/bb73d2/32.png) [@349iq2345](https://forum.onefinitycnc.com/u/349iq2345)\ **Post date:** [May 6, 2023, 5:12pm UTC](https://forum.onefinitycnc.com/t/y-axis-left-rail-moves-with-a-jerky-motion/20464/2 "2023-05-06T17:12:50Z")
Hey Frank, > [@Frank3](#): > > New setup on Elite forman. I noticed during assembly that when I move the gantry by hand (unplugged) that the left side was catchy and grabby along most of the travel. When moving under power it has a kind of pulsing movement on the left side up can feel in the overall machine. Also looks like the ball screw is slightly wobbly. Right side is smooth as silk. Besides a ball screw that is simply bent a little too much (should be replaced if it makes such errors, write to [support@onefinitycnc.com](mailto:support@onefinitycnc.com) if you cannot find another cause), I could think of point 7) (ball end nut too tight) in this document - [Troubleshooting: Rail is getting hung, stuck, or out of alignment (x35/x50 machines)](https://forum.onefinitycnc.com/t/troubleshooting-rail-is-getting-hung-stuck-or-out-of-alignment-x35-x50-machines/10826) I would also check point 4) (coupler). There was a case when a part had become loose and has hindered the rotation of the screw. Since your machine is new, it is unlikely that it is point 5) (ball screw). However once there occured [this mysterious issue](https://forum.onefinitycnc.com/t/help-losing-home-during-carves/7022/70). It was solved by the manufacturer replacing the entire rail. --- _[View the full topic](https://forum.onefinitycnc.com/t/y-axis-left-rail-moves-with-a-jerky-motion/20464)._