I for one don’t want to have a download a video to see the issue, perhaps IMGR or another host would be preferable?
It looks like the bottom support wheel is loose or missing. The guide wheels are still on top, however there should be a bottom wheel under the rail that provides tension.
Thank you so much. It was that. It was my first time uploading a video in here, i promise ext time put in Imgr . I really apreciatte your time to respond me.