Y2 stepper motor making a clicking sound

I’m the proud owner of a new Lowrider 3 that I’ve been putting together over the last 6 months. I’ve been running it non-stop over the past week. At one point it tried to drive itself off the table, stretching both belts in the process, so I had to replace them. Since then, the Y2 stepper motor has been making a clicking noise (you can hear it in this video). The Y1 stepper is not clicking. The Y1 and Y2 motors are identical, the belts are the same, and as far as I can tell the tension is the same.

Any ideas what might be happening? Should I be worried?

I’ve read on 3D printer forums that stepper motor clicking can indicate missed steps, but I’m not sure how to tell whether that’s the cause.

I’m using the following stepper motors from AliExpress (unfortunately the original link is dead): Nema 17 Stepper Motor 4-lead 48mm 59Ncm(84oz.in) 2A


and this belt:

Any advice would be greatly appreciated.

Cheers,
Mike

[EDIT] Solved! It was a loose grub screw on the Y2 stepper motor pulley. I feel like I should have known to investigate that, but I don’t know why…