You will have to unscrew the 4 screws on your pullstarter, as you start to unscrew them the string to the pull starter should go back in automaticly.
If it doesn't then you need to get a new pull starter and put it on. Its very simple to remove and add a new one.
If your steering servo is weak, it might be your dual rate. There is a little nob on your radio controller that controllers how fast or slow the steering servo turns.