Hi @David,
I’m on an iPad and can’t get your links to play, but from your description it sounds like maybe you are having the same problem as I am, which is well described here:
Is that what yours is doing? If so, it’s just a damaged wire connecting to the z-axis motor, @Jorge will have you sorted out in no time!
I received a shipping notice for a new wire assembly a few days ago, and instructions today to install it, should be back up and running before the week is over.
I hope this helps - as I said I can’t be sure because the video won’t play for me.