fighting z wobble

Started noticing some moderate z wobble on my prints with my taz 5.

So far I’ve tried:
cleaning/lubricating the z screws
loosening/tightening the z steppers (after every adjustment have to align the x axis/re-level the bed)
checked for lose parts
tightened x belt
I noticed that the upright 80-20 is not quite vertical/square

Things on my list to try:
printing cal cube at 45 degree angle
printing rectangle 8" high to see if the z wobble is all the way to the top
try reseating the z steppers multiple times to get better alignment
go through the 80 20 upright frame to see if I can make it more square
replace the z screws/couplers

Thoughts? I looked back at some of the original prints that I did with the taz 5 and noticed some slight z wobble, the problem appears to be getting worse. One of the z couplers was pretty obviously compensating for misalignment (bent) loosening the stepper and reseating it had no real effect.

Besides the cosmetic defect, really has effect on prints with two flat walls that are supposed to be in a flush assembly.

That doesn’t look bad, IMO. Try lubricating the z-axis, clean the belts tension

probably not an issue on Z, but the pulley on my Y-axis was jambed down against the bearing causing some serious wobbles. For 180 degrees the pulley was contacting the bearing

Looks like you may have a little wobble in the pictures. Try running the Z_burnin_test code on the SD card, and as it travels up and down during the code execution look for side to side motion of the head/Z-Rods.