question on cracks in HP pump

[B-Hive]

Thanks to that fantastic link on pulling apart an HP pump. I'm just about ready to get started on it..

However on close inspection of the pump that purportedly is cracked, despite a very thorough examination of it, I cannot for the life of me see where it might be cracked. So I dont want to go to al the effort and swap its internals for no good reason..

Can anyone tell me where I should be looking for the crack or are they generally so fine that they are not visible to the naked eye??

Thanks