[MrBasse]

What if you ran the motor remotely? Use a cable like a bike brake system and have the motor off the arm. That way you can transfer force to the claw system and have it spring loaded to open or close while the motor and cable provide the opposite action. We used this for 2011 to grip tubes and it was incredibly flexible and allowed us to pinch tubes as tight as we could have wanted. Plus parts are cheap, you can get cable and clamps at Lowes, Home Depot, or any local bike shop.