Having some issues with the left hub. I cannot get it to clamp to the axle. I cleaned out some debris from the screw hole and slot but no joy. I actually snapped the head off a screw trying to get it to clamp. (got it back out thankfully) Is there a trick here I don't know? I'm a TC racer and this is my first pan car. I assume I am missing something obvious. Any help is appreciated.