There are some instances when the spring which allows a person to fire a Nerf crossbow breaks. One you have opened up the Nerf crossbow you will be able to tell whether or not the spring has broken. If in fact you are dealing with a broken swing then you are in luck since it can be replaced.
There are 19 1.0 cm screws in total.
Separate each part of the Nerf crossbow.
Take the broken spring off of the trigger.
Replace it with the new spring you bought at your local hardware store.
Now that the spring has been reattached to the trigger repeat step two.
Finish by performing steps two and three in reverse order.