If you're facing a DUI charge, I recommend you get an attorney. This is not something you'll effectively do pro se.
You should read NC Gen. Stat 20-139.1, which covers how to protest the breath test readings. The Dept. of Health and Human services sets the standards, and the statute puts the burden of proof on YOU if you want to allege the readings are incorrect due to lack of maintenance. The case law is pretty much against you as well. If you are going to challenge this, it behooves you to understand how to determine what is and isn't acceptable evidence and/or witnesses. It's more than we can teach you in a net posting.
Further, an attorney will look at the case and attack it at more than just some imagined error in the breathalyzer.