Is the line rubbing anywhere against the plastic? ? When that would happen to me the line would be cutting into the plastic making it stick the line isn't flowing freely gettin snagged on something or the motor is about to burn out so it's sticking.
My cars are the other way around... If I want em to lock up I use more line than neccesary, if I wanna hop with automatic dump I use just enough line to get the job done and have the tires rub the wheelwells so it lays... And as far as paper clips and shit, I'd suggest you take the motor out of your old chassis, go to the hobby shop and get a HH chassis with no motors or nothing already on it or anything for like 6 bucks, and put your old motor on that chassis and then take some brass rod or an old wire clothes hange and make a new u-bar and the sutff on the HH chassis should be pre made a drilled so no more messin with ugly stupid guides that come off and don;t work half the time, on the HH chassis the guides are made into the plastic! Hope this Helps, GOod luck!