Search:

I guess just learn how far from bottom or top it is and you will have a reference point i.e my Zeiss doesn't have zero stop installed but I know its 21 MOA from the bottom so can always do a re check.

Take off the dial, the ring is the first thing you see, it has one section raised into a post. Jimmy it up carefully moving around it with a flat head or the like.

You can see the ring with post...

The ball is in the right place, the post wont be, I had to lift that ring off carefully and re set it so the post stopped the ball at zero

I got a zero stop ball bearing free from nz asia