I had a similar problem. So this is what I did:
- I took the little ruler that comes with the taz and made a little jig that slips over it with tension and allows me to set a “stop” point.
- Move your Z-axis to to the home position and disengage your motors.
- Place the end of the ruler on top of the metal plate (I prefer using the left side), and move the stop you put on the ruler until it touches the X-Axis lower rod. This is your reference height
- Next, move your ruler to the right side and repeat the measurement. Rotate the coupler where the Z-axis motor connects to the threaded shaft by hand until the rod hits the stop on your ruler.
Now your X-Axis is level with the metal plate (and presumably, with the whole rig)
Now, I would suggest you screw your bed screws all the way down. Don’t get aggressive, just get them all to a baseline. Now, Unscrew each one the same number of rotations until you have half the screw raised. No it’s not scientific, but will get you really close to level.
Now reset your stop point screw by following the directions. You should find that once you get the gross height worked out with the stop screw ans piece of paper, the bed leveling screws will only need minor tweeks to get consistnat height around your bed.