How many shims are needed, and when, for the 4827 Front Bearing Block?

When I purchased the car the front belt was rubbing on the edge of the servo.* I* noticed that there are no shims under the Front Bearing Block.

I replaced the front belt and purchased a new Bearing Block so that I could get the shims.* But I do not know how many to install or why the belt was rubbing on the steering servo

Any help would be appreciated
Thanks
Tony