We sent this to your support ticket. The big thing here is that you only sent support the first two videos. You completely left off the send two, so they are working with much less information than you gave everyone here?
The videos are so incredibly short and show very little wholistically that there’s not much we can troubleshoot from them.
I would say go through this FAQ for that rail.
Send a detailed, narrated video for each step of the faq. The more you can show the better. I’d aim for at least 2-3 minutes per video so we can see much much more.
One of the main things we haven’t seen is that, with the ball nut removed, can you jog the gantry block with bearings back and forth freely?