RE: twisted limb ?
Looking pretty much straight down the string, you should be able to see the limb tip tracking the center of the face of the limb nearest you, and the string tracking the center of the belly of the limb furthest away.
If the string tracks the center of the far limb, but the tip of the near limb is off to one side...it's twisted.
Easy to do, hard to explain without a picture. Hope this helps.
JRW