having the latest firmware is a good starting point,
doing a factory reset ensures that the firmware is in a known status,
Is it possible that the Y axis frame has become twisted?
with the printer on a smooth level surface? Try pressing alternate opposite corners down.
to see if the frame rocks at all.
ensure that the aluminium main frame is located correctly, with the screwed threaded rods located in the bottom of the cut outs, so that the aluminium frame is suspended in mid air... not resting on the table,
using the Control knob on the front panel raise the X carriage to the top and make sure that you keep in raising the 'Z' height until both Z motors stall because the X axis has reached the Z axis end stops. at the top of the frame.
then when all is ready, make sure the extruder nozzle is clean, and do a fresh self test and XY calibration then a Z calibration, then set your Live 'Z'
best wishes, Joan
I try to make suggestions that I believe to be well founded and safe,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions,
what you do, is YOUR responsibility.