Noticed when tightening up the pinch bolt on the gear change lever it walks off the shaft, and remembered post by folks losing the lever on route.
So put the lever on without pinch bolt, slipped a small round file down the hole to mark the shaft, removed the lever and filed a grove in the shaft with a bit bigger file, only made a groove where the pinch bolt goes not all the way around. Shaft is quite soft so go steady with the file
Thinking this will give the bolt a little bit of hold on the shaft, used a new bolt as the old one was waisted a bit where it had been fouling the shaft as it was screwed in.
Time will tell