woodman .
  the spring is  very easy to make . infact he can make a better one way cheeper then buying a new one .
 have him go down and get a piece of piano wire .
 most harware stores carry K&S
 if not , if he has a hobby store close that cells RC cars and planes .
3 ft should run him around 50 cents .
just bend it slowly with a set of pliers and he will have a speing that much smoother and with a better responce  then the  factory