Carefully separate the bottom half of the gun from the top half, leaving the cylinder and gears in place.

The anti-reversal latch (left, photo 3) has a spring on it that forces it out of place. If it falls out of the gearbox, put it back in facing the first gear.

The trigger (right, photo 3) has a spring that likes to push the trigger away from the gearbox. Keep an eye on it and put it back in if needed.