Here's the problem and this is where the fuel line comes in handy. Your dog bones are walking DOWN towards the axle hub (because naturaly they want to move in a downward direction) which is allowing it to rub on the edge of the drive cups. So you put a sliver of fuel line in all the drive the hubs to help hold the dogbones in the proper position. You don't want to to big a pieces or you will end up with bound up wheels. You want just enough to be able to take up the slack and the wheels should move freely when the arms are in the upper and lower positions.