How to Correctly Change Your Seiko NH35 Watch’s Rotor

Many watch lovers like the idea of customizing their watches to their liking. While others prefer to keep the original design, some simply want their timepieces to reflect their unique personality.

If you, too, are excited about the idea of personalizing your watch, you can start with one of the simplest customization projects that you can DIY—replacing your Seiko NH35 rotor. 

You can get a new rotor and other mod parts from SeikoMods. Once you get yours, you can prepare these tools needed and proceed with changing the rotor:

What You Need

  • Screwdriver
  • Tweezers
  • Case back opener or a friction ball
  • Finger cots or peg wood
  • Rodico and hand pump

How to Change Your Custom Rotor

1. Remove the Case Back Carefully

Align the case back opener’s pins to the three notches that you see on the case back. Turn the thumbwheel to adjust the span of the two pins. This will help the pins fit into two notches on the case back first before turning the handle so you can then adjust the bottom pin’s position. 

Once all the pins are aligned with the notches, apply firm pressure to the case back opener with your index finger as your thumb is pressing against the crystal so the case back opener won’t slip, and you can avoid scratches. 

Loosen the case back by carefully turning the case counterclockwise. Once you have it loosened, you can then start unscrewing the case back with your hands. Remember to put the case down with the internal side facing down to prevent it from getting dusty. 

2. Choose the Right Screwdriver

You will have to unscrew the central screw securing the NH35 rotor to the movement. You can only do that with the right screwdriver that fits perfectly because the wrong one can slip and scratch both the rotor and the screw. 

Check the width of the central screw. Your screwdriver must fit into that perfectly. For the NH35 rotor, use a screwdriver with a tip that is slightly bigger than 2.5 mm but still thin enough to get in the slot. 

3. Remove the Rotor

As you are holding the watch by the case, carefully insert the screwdriver into the slot and turn it counterclockwise. Make sure you maintain a firm pressure from the screwdriver’s end. It should also be perfectly perpendicular to the rotor to avoid slipping and to ensure that the screw is correctly installed. Keep turning until the rotor is unscrewed then remove it using the tweezers. Remember not to touch either the rotor or the movement with your fingers or you’ll leave stains on them.

4. Put the New Rotor On

Now it’s time to get that new custom rotor on the movement. Carefully pick it up using the tweezers and lay it slowly onto the screw’s central post. Secure it by screwing it loosely.Start applying downward pressure and keeping the screwdriver perpendicular and keep turning the screwdriver until there’s resistance. You can then use your finger cot to rotate the rotor and see if the gears are properly engaging. Once you confirm this, you can keep tightening the screw but be careful not to overdo it or you might damage the screw thread. 

5. Do a Final Check

After making sure that everything is working as they should, inspect for any lint or dust on the movement and the rotor. This is important because not only will it affect the appearance but also the watch’s function. Use your hand pump and Rodico before putting the case back in place. 

Once you’re done, shake the watch lightly and listen for any sounds that the rotor might be making. There shouldn’t be any metal scratching sound or some rattling which is an indication of a loose rotor. 


There you have it. By following these steps, you can change your rotor with a customized one! Mind that you follow these carefully because one wrong move could end up scratching your rotor or movement. If you are not confident that you can do it flawlessly, you might want to just bring your Seiko mods to a reputable horologist who can replace the rotor for you. 

Whether you want to customize your watch or some parts need replacement, can provide you with Seiko mod parts of the highest quality. All our parts will pass the standards of the most discerning eye. Check out our products today!

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