Regarding the symptoms you describe, I don’t think I would replace the controller. These issues are frequent and their cause is in most cases either
the tin-plated stock connectors that are unreliable and make errors after a longer use, especially on moving parts with no strain relief (as found on left X axis foot) or
electromagnetic interference (EMI), or
internal cable break on the “curly” Z cable.
If you use the search function of the forum, you will information about these three possible causes.
Did you ensure this:
By not observing this accidentally, the other day I got a Raspberry Pi B where the HDMI output permanently ceased to work. Still working for remote User Interface control.