Press on the air nozzle to ensure that it slides back and springs forward when released.

Reinstall the main spring and spring guide. Placing a tool such as a thin screwdriver into the rear of the spring guide can assist in pushing the spring in and holding the guide down.

Place the right half of the gearbox back on top. It is best to start from the rear, at the spring guide, then pull the gearbox half forward over the cylinder head.

Make sure all of the gears, anti-reversal latch, and trigger line up in their respective holes.