Scope question??

[bigj]

I just got my zeiss conquest back from warranty work and the paper work says the "erector system" was replaced/repaired.I was wondering what that is and what it does??The scope would never stay on for more than a couple shots then way out again.Hoping it wasnt my rifle i sent the scope in.So i sure hope this is the fix i needed.Havent had a chance to try it yet,so any info is greatly appreciated!!Thanks for you help.