Rear Modolo brake pinch bolt won’t pinch 🤔

[legrandefromage]

a washer is required

 

[bikeworkshop]

I’ve had it apart again this afternoon noon. The slot and nut appear to be in good order with minimal wear so I conclude the brake cable gauge is too small to be clamped effectively. There’s no problem with the front brake on the same cable. I’ve measured the cable diameter at just 1.4mm.

Shimano brake cable is 1.6mm
That usually works.

1.4 seems a little narrow.
It's lost in the groove