Levelling the swashplate on an RC helicopter is an important step to ensure proper control and stability during flight. Here’s a general procedure to help you level the swashplate:

1. Prepare your RC helicopter: Ensure the helicopter is securely mounted or held in place to prevent it from moving during the leveling process. You can use a heli stand or have a helper hold it steady.

2. Power on the helicopter: Turn on the transmitter and then power up the helicopter. Make sure the throttle stick is in the lowest position, and the trim tabs are centered.

3. Access the swashplate: Remove any canopy or cover that might be obstructing access to the swashplate. Depending on the helicopter model, this may involve removing screws or clips.

4. Adjust the servo links: Locate the servo arms that are connected to the swashplate and adjust the servo link lengths. These are usually threaded rods with adjustable linkages at both ends. 

5. Leveling process: The goal is to make the swashplate level with respect to the helicopter’s mainshaft. Follow these steps:

   a. Check the swashplate movement: Move the collective stick (throttle stick) up and down gently to observe how the swashplate moves. It should move smoothly and without any binding.

   b. Observe swashplate tilt: Move the cyclic stick (aileron or elevator) to one side and observe the swashplate. It should tilt slightly in the direction of stick movement.

   c. Adjust the servo link lengths: If the swashplate tilts excessively or in the wrong direction, you need to adjust the servo link lengths. For example, if the swashplate tilts to the left when moving the cyclic stick to the right, you would need to shorten the link that connects the right servo to the swashplate. Make small adjustments to the link length and recheck the swashplate tilt until it is level or slightly tilted in the correct direction.

   d. Repeat for each servo: Go through the same process for each servo arm connected to the swashplate, adjusting the link lengths as needed.

6. Test and fine-tune: After making adjustments, power off the helicopter, power it back on, and repeat the swashplate leveling process. Continue fine-tuning the link lengths until the swashplate moves smoothly and tilts correctly in response to cyclic stick movements.

7. Secure the linkages: Once you’re satisfied with the swashplate leveling, tighten the locknuts or set screws on the servo linkages to secure them in place. Double-check that everything is tight but not overly tight.

8. Reassemble the helicopter: Put the canopy or cover back on and ensure all screws or clips are properly secured.

Remember, this procedure may vary slightly depending on the specific model of your RC helicopter, so consult your helicopter’s manual if you encounter any discrepancies. Additionally, it’s always a good idea to seek advice from experienced RC helicopter pilots or hobbyists who can provide guidance tailored to your specific model and setup.