In some cases when you pull the cocking mechanism back it may not lock. When this happens first check to make sure that you have pulled the mechanism back far enough to lock. After you have checked and it is still not locking open up the crossbow making sure to follow the steps in this guide.
There are 19 1.0 cm screws.
The cocking device air to be built up inside the Nerf crossbow, which generates the force needed to propel the darts.
Use the screwdriver and unscrew each screw one-by-one placing each screw on the magnetic mat to insure they do not get lost.
Separate each part of the Nerf crossbow.
Make sure the cocking mechanism is properly aligned with the rest of the Nerf crossbow.
The cocking device needs to be attached to the plunger in order to function properly.