Don't believe the fluff about Glock certified armorers. A trained monkey could take one down and put it back together. Glockmeister's instructions are fine.
I was at a class a while back, and my 23 was hanging up just out of battery. There were 2 certified Glock armorers on site. Each one took a turn. Field stripped it, blew on the internals, turned it over in their hands a couple of times, handed it back and said, "I don't know." WTF??