make sure your gear mesh is set corect. the cup i dont know about. the bubbles could be from a cracked line or a bad seal on the fuel tank lid. the glow plug could be bad also. the pull start is not grabbing because the oil from the traxxas fuel has so much oil in it that it gets into the one way bearing so then it slips and doesnt catch. the binding is most likely because your brakes are improperly set up. try loosening them up a little bit.