Sure ! I noticed you said that it was hitting your thumb,first make sure you have the arm bolt through the first hole ,the one furthest from the turn buckle screw and that should help and the other is to get rid of the over draw plate so there's no vibration's. Be sure to cover the shelf and the hook with mole skin as well .Be sure not to tighten the bolt from the arm, the arm need's to drop's freely ,just be sure it's not too tight .Other than that this rest is very easy to setup and I'm sure you'll really like it .

nubo