Modern Vespa

The front brake works fine, but the break lever is broken. I have a replacement. I went to unscrew the nut securing the cable at the wheel, but it's on a delicate appendage secured with a small pin, and difficult to unscrew, very tight, and rotates with the appendage arm at the pin secure. Is there another screw I can release instead to allow the whole cable link to release? Since I'm not replacing the brake cable. Or is there a trick to unscrew the nut holding the cable?

Put a wrench on the backside. It's a bolt with a hole in it.

All fixed!
I just needed a little confidence and a little support.
Appreciate your guidance!