Have you determined whether the cable is binding, the springs are too tight, or the butterfly/linkage is binding?
If the cable needs to be lubed or replaced, that would definately make it more difficult to pull the throttle. Also if the springs were replaced with ones that are not correct it would also be difficult to pull. If all that is the way that it's supposed to be, I would suggest getting lighter springs from another model.
Does that sled have Tillotson or Mikuni butterfly carbs on it?
You don't have to flinch for me to know that you're scared.