Ticking on Z-Axis

I’ve gone through the older posts on this, but still have not resolved the issue.

My TAZ 5 has started making a ticking sound when the Z axis moves. It has been getting progressively louder in the last couple days. I’ve checked to make sure all of the fasteners are tight, that the coupler is not cracked, lubed the lead screw, but the ticking continues.

When using the LCD control to move the Z-axis the ticking sound is consistent with every half revolution of the stepper motor. This is happening on the left side only. Could I have a failing stepper motor?

Anything else I can troubleshoot?

Have you checked the bearings at the top of the leadscrews?

Thanks for the suggestion! The sound is coming from the bottom end of the machine. After taking some closeup pictures for customer support it’s apparent there are cracks in the coupler. The X-axis was 1-2mm off level which may or may not have contributed to the problem. Their suggestion is to re-align the stepper motor to the lead screw which I will do as soon as I get a replacement coupler.