Flex Coupler issues

Things seem to be moving along now. However, I’ve noticed an issue with the left flex coupler for the Z-axis. It stretches and pops during a full rotation, while the one on the right does not. After a full rotation, the coupler stretches and then snaps back.

The result is that the movement becomes slightly lopsided, and the issue worsens exponentially throughout the job. The coupler isn’t broken; it almost seems like it’s too tight.

Do you have any suggestions for fixing this issue?

Thanks rj